title: Uninstall all installed gems, in OSX?
body: <p>There are instances where I would like to revert and uninstall all previous gem installations.</p>
  
  <p>For instance, I needed to assist a friend migrate their rails development machine to use RVM.  As they had been previously using the system-wide <code>gem</code>, he was experiencing many headaches when working with multiple projects.  <em>Essentially, he was the poster-child for an RVM convert.</em></p>
  
  <p>How can I elegantly uninstall all of the gems on his OSX system?</p>