title: Can't install gems on OS X "El Capitan"
body: <p>I am not able to install and run <code>fakes3</code> gem on El Capitan Beta 5.</p>
  
  <p>I tried:</p>
  
  <pre><code>sudo gem install fakes3
  ERROR:  While executing gem ... (Errno::EPERM)
      Operation not permitted - /usr/bin/fakes3
  </code></pre>
  
  <p>Then I tried doing it the cocoapods way. It worked for cocoapods but not for fakes3.</p>
  
  <pre><code>mkdir -p $HOME/Software/ruby
  export GEM_HOME=$HOME/Software/ruby
  gem install cocoapods
  [...]
  1 gem installed
  gem install fakes3
  ERROR:  While executing gem ... (Gem::FilePermissionError)
      You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory.
  </code></pre>