Heroku Push error "Detected sqlite3 gem which is not supported on Heroku."

I am trying to push my app to Heroku. I have used the sqlite gem in development and the pg gem in production but I am still getting the:

Detected sqlite3 gem which is not supported on Heroku.

Error.

remote:        An error occurred while installing sqlite3 (1.3.10), and Bundler cannot
remote:        continue.
remote:        Make sure that `gem install sqlite3 -v '1.3.10'` succeeds before bundling.
remote:  !
remote:  !     Failed to install gems via Bundler.
remote:  !     
remote:  !     Detected sqlite3 gem which is not supported on Heroku.
remote:  !     http://ift.tt/1bCjY9s
remote:  !
remote: 
remote:  !     Push rejected, failed to compile Ruby app
remote: 
remote: Verifying deploy...
remote: 
remote: !       Push rejected to fierce-thicket-3015.
remote: 

Here is my Gemfile:

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.1.7'
# Use sqlite3 as the database for Active Record
group :devlopment, :test do
  gem 'sqlite3'
end

group :production do
  gem 'pg',             '0.17.1'
  gem 'rails_12factor', '0.0.2'
end

# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.3'
gem 'bootstrap-sass'
gem 'autoprefixer-rails'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'
# See http://ift.tt/MqZZdN for more supported runtimes
# gem 'therubyracer',  platforms: :ruby

# Use jquery as the JavaScript library
gem 'jquery-rails'
gem 'jquery-ui-rails'
gem 'jcrop-rails-v2'
# Turbolinks makes following links in your web application faster. Read more: http://ift.tt/OVlBaz
gem 'turbolinks'
# Build JSON APIs with ease. Read more: http://ift.tt/GXyveo
gem 'jbuilder', '~> 2.0'
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', '~> 0.4.0',          group: :doc

# Spring speeds up development by keeping your application running in the background. Read more: http://ift.tt/1fzTFBA
gem 'spring',        group: :development

# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use unicorn as the app server
# gem 'unicorn'

# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development

# Use debugger
# gem 'debugger', group: [:development, :test]

gem 'devise'
gem 'devise_invitable'
gem "mini_magick"
gem 'carrierwave'
gem 'will_paginate-bootstrap'
gem 'acts_as_commentable'
gem 'acts_as_votable'
gem 'acts-as-taggable-on'

group :development do
  gem "better_errors"
  gem "binding_of_caller"
  gem "letter_opener"
end

and here is my Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    actionmailer (4.1.7)
      actionpack (= 4.1.7)
      actionview (= 4.1.7)
      mail (~> 2.5, >= 2.5.4)
    actionpack (4.1.7)
      actionview (= 4.1.7)
      activesupport (= 4.1.7)
      rack (~> 1.5.2)
      rack-test (~> 0.6.2)
    actionview (4.1.7)
      activesupport (= 4.1.7)
      builder (~> 3.1)
      erubis (~> 2.7.0)
    activemodel (4.1.7)
      activesupport (= 4.1.7)
      builder (~> 3.1)
    activerecord (4.1.7)
      activemodel (= 4.1.7)
      activesupport (= 4.1.7)
      arel (~> 5.0.0)
    activesupport (4.1.7)
      i18n (~> 0.6, >= 0.6.9)
      json (~> 1.7, >= 1.7.7)
      minitest (~> 5.1)
      thread_safe (~> 0.1)
      tzinfo (~> 1.1)
    acts-as-taggable-on (3.4.3)
      activerecord (>= 3.2, < 5)
    acts_as_commentable (4.0.2)
    acts_as_votable (0.10.0)
    addressable (2.3.6)
    arel (5.0.1.20140414130214)
    autoprefixer-rails (5.1.1)
      execjs
      json
    bcrypt (3.1.10)
    better_errors (2.1.1)
      coderay (>= 1.0.0)
      erubis (>= 2.6.6)
      rack (>= 0.9.0)
    binding_of_caller (0.7.2)
      debug_inspector (>= 0.0.1)
    bootstrap-sass (3.3.3)
      autoprefixer-rails (>= 5.0.0.1)
      sass (>= 3.2.19)
    builder (3.2.2)
    carrierwave (0.10.0)
      activemodel (>= 3.2.0)
      activesupport (>= 3.2.0)
      json (>= 1.7)
      mime-types (>= 1.16)
    coderay (1.1.0)
    coffee-rails (4.0.1)
      coffee-script (>= 2.2.0)
      railties (>= 4.0.0, < 5.0)
    coffee-script (2.3.0)
      coffee-script-source
      execjs
    coffee-script-source (1.9.0)
    debug_inspector (0.0.2)
    devise (3.4.1)
      bcrypt (~> 3.0)
      orm_adapter (~> 0.1)
      railties (>= 3.2.6, < 5)
      responders
      thread_safe (~> 0.1)
      warden (~> 1.2.3)
    devise_invitable (1.4.0)
      actionmailer (>= 3.2.6, < 5)
      devise (>= 3.2.0)
    erubis (2.7.0)
    execjs (2.2.2)
    hike (1.2.3)
    i18n (0.7.0)
    jbuilder (2.2.6)
      activesupport (>= 3.0.0, < 5)
      multi_json (~> 1.2)
    jcrop-rails-v2 (0.9.12.3)
    jquery-rails (3.1.2)
      railties (>= 3.0, < 5.0)
      thor (>= 0.14, < 2.0)
    jquery-ui-rails (5.0.3)
      railties (>= 3.2.16)
    json (1.8.2)
    launchy (2.4.3)
      addressable (~> 2.3)
    letter_opener (1.3.0)
      launchy (~> 2.2)
    mail (2.6.3)
      mime-types (>= 1.16, < 3)
    mime-types (2.4.3)
    mini_magick (4.0.3)
    minitest (5.5.1)
    multi_json (1.10.1)
    orm_adapter (0.5.0)
    pg (0.17.1)
    rack (1.5.2)
    rack-test (0.6.3)
      rack (>= 1.0)
    rails (4.1.7)
      actionmailer (= 4.1.7)
      actionpack (= 4.1.7)
      actionview (= 4.1.7)
      activemodel (= 4.1.7)
      activerecord (= 4.1.7)
      activesupport (= 4.1.7)
      bundler (>= 1.3.0, < 2.0)
      railties (= 4.1.7)
      sprockets-rails (~> 2.0)
    rails_12factor (0.0.2)
      rails_serve_static_assets
      rails_stdout_logging
    rails_serve_static_assets (0.0.4)
    rails_stdout_logging (0.0.3)
    railties (4.1.7)
      actionpack (= 4.1.7)
      activesupport (= 4.1.7)
      rake (>= 0.8.7)
      thor (>= 0.18.1, < 2.0)
    rake (10.4.2)
    rdoc (4.2.0)
      json (~> 1.4)
    responders (1.1.2)
      railties (>= 3.2, < 4.2)
    sass (3.2.19)
    sass-rails (4.0.5)
      railties (>= 4.0.0, < 5.0)
      sass (~> 3.2.2)
      sprockets (~> 2.8, < 3.0)
      sprockets-rails (~> 2.0)
    sdoc (0.4.1)
      json (~> 1.7, >= 1.7.7)
      rdoc (~> 4.0)
    spring (1.2.0)
    sprockets (2.12.3)
      hike (~> 1.2)
      multi_json (~> 1.0)
      rack (~> 1.0)
      tilt (~> 1.1, != 1.3.0)
    sprockets-rails (2.2.4)
      actionpack (>= 3.0)
      activesupport (>= 3.0)
      sprockets (>= 2.8, < 4.0)
    sqlite3 (1.3.10)
    thor (0.19.1)
    thread_safe (0.3.4)
    tilt (1.4.1)
    turbolinks (2.5.3)
      coffee-rails
    tzinfo (1.2.2)
      thread_safe (~> 0.1)
    uglifier (2.7.0)
      execjs (>= 0.3.0)
      json (>= 1.8.0)
    warden (1.2.3)
      rack (>= 1.0)
    will_paginate (3.0.7)
    will_paginate-bootstrap (1.0.1)
      will_paginate (>= 3.0.3)

PLATFORMS
  ruby

DEPENDENCIES
  acts-as-taggable-on
  acts_as_commentable
  acts_as_votable
  autoprefixer-rails
  better_errors
  binding_of_caller
  bootstrap-sass
  carrierwave
  coffee-rails (~> 4.0.0)
  devise
  devise_invitable
  jbuilder (~> 2.0)
  jcrop-rails-v2
  jquery-rails
  jquery-ui-rails
  letter_opener
  mini_magick
  pg (= 0.17.1)
  rails (= 4.1.7)
  rails_12factor (= 0.0.2)
  sass-rails (~> 4.0.3)
  sdoc (~> 0.4.0)
  spring
  sqlite3
  turbolinks
  uglifier (>= 1.3.0)
  will_paginate-bootstrap

I'm quite new to rails and I can't work out what is going wrong here since Sqlite is only being used in development not production. If anyone can help me out I'd really appreciate it, I've tried searching and cant work out what is causing this. Thanks!