title: Error related with spring when trying to execute rails commands
body: <p>I have created a new rails application folder, which worked smoothly. Once within such folder, running any kind of rails command like <code>rails s</code> will prompt me:</p>
  
  <pre><code>You've tried to invoke Spring when it's already loaded (i.e. the Spring constant is defined).
  
  This is probably because you generated binstubs with Spring 1.0, and you now have a Spring version &gt; 1.0 on your system. To solve this, upgrade your bundle to the latest Spring version and then run `bundle exec spring binstub --all` to regenerate your binstubs. This is a one-time step necessary to upgrade from 1.0 to 1.1.
  </code></pre>
  
  <p>I currently have</p>
  
  <pre><code>spring -v
  Spring version 2.1.0
  </code></pre>
  
  <p>I've tried the following, getting the same results. I also tried uninstalling spring and reinstalling.</p>
  
  <pre><code> bundle exec spring binstub --all
  * bin/rake: Spring already present
  * bin/rails: Spring already present
  </code></pre>