title: Gem::LoadError for mysql2 gem, but it's already in Gemfile
body: <pre><code>Gem::LoadError
  Specified 'mysql2' for database adapter, but the gem is not loaded.
  Add `gem 'mysql2'` to your Gemfile
  </code></pre>
  
  <p>This error occurred while loading the following files:</p>
  
  <pre><code>active_record/base
  </code></pre>
  
  <p>This is the error I get on running rails server.</p>
  
  <pre><code>The mysql2 gem has been added to the Gemfile as well.
  </code></pre>
  
  <p>I've done <code>bundle install</code>, and tried restarting the server but still get the error.</p>