title: failed push to heroku using rails 4
body: <p>i try to deploy my rails app to heroku, but when <code>git push heroku master</code> i get error like this :</p>
  
  <pre><code>-----&gt; Ruby app detected
  -----&gt; Compiling Ruby/Rails
  -----&gt; Using Ruby version: ruby-2.0.0
  -----&gt; Installing dependencies using Bundler version 1.3.2
         New app detected loading default bundler cache
         Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin --deployment
         You are trying to install in deployment mode after changing
         your Gemfile. Run `bundle install` elsewhere and add the
         updated Gemfile.lock to version control.
         You have added to the Gemfile:
         * pg
         * carrierwave
         * debugger
         * rails_12factor
         Bundler Output: You are trying to install in deployment mode after changing
         your Gemfile. Run `bundle install` elsewhere and add the
         updated Gemfile.lock to version control.
  
         You have added to the Gemfile:
         * pg
         * carrierwave
         * debugger
         * rails_12factor
   !
   !     Failed to install gems via Bundler.
   !
  
   !     Push rejected, failed to compile Ruby app
  </code></pre>
  
  <p>why i get error like this? i already to try <code>bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin --deployment</code> and run <code>git push heroku master</code> again but i still get same error like before???</p>
  
  <p>i'm using ruby 2.0 and rails 4, please tell me if i'm wrong? thanks before</p>
  
  <p><strong>Edit:</strong></p>
  
  <p>my gemfile: </p>
  
  <pre><code>source 'rubygems.org'; 
  gem 'rails', '4.0.1' 
  group :development do 
    gem 'sqlite3' 
  end 
  group :production do 
    gem 'pg' 
  end 
  gem 'sass-rails', '~&gt; 4.0.0' 
  gem 'uglifier', '&gt;= 1.3.0' 
  gem 'coffee-rails', '~&gt; 4.0.0' 
  gem 'jquery-rails' 
  gem 'turbolinks' 
  gem 'jbuilder', '~&gt; 1.2' 
  group :doc do 
    gem 'sdoc', require: false 
  end 
  gem 'devise' 
  gem "twitter-bootstrap-rails" 
  gem 'carrierwave' 
  gem 'debugger', 
  group: [:development, :test] gem 'rails_12factor'
  </code></pre>