title: What is "USER INSTALLATION DIRECTORY" in rubyGems env
body: <p>Here's my RubyGems Environment:</p>
  
  <ul>
  <li>RUBYGEMS VERSION: 2.5.2</li>
  <li>RUBY VERSION: 2.2.2 (2015-04-13 patchlevel 95) [x86_64-darwin14]</li>
  <li>INSTALLATION DIRECTORY: /Users/wh026399/.rvm/gems/ruby-2.2.2</li>
  <li><strong>USER INSTALLATION DIRECTORY</strong>: /Users/wh026399/.gem/ruby/2.2.0</li>
  <li>RUBY EXECUTABLE: /Users/wh026399/.rvm/rubies/ruby-2.2.2/bin/ruby</li>
  <li>EXECUTABLE DIRECTORY: /Users/wh026399/.rvm/gems/ruby-2.2.2/bin</li>
  <li>SPEC CACHE DIRECTORY: /Users/wh026399/.gem/specs</li>
  <li>SYSTEM CONFIGURATION DIRECTORY: /etc</li>
  <li>RUBYGEMS PLATFORMS:
  
  <ul>
  <li>ruby</li>
  <li>x86_64-darwin-14</li>
  </ul></li>
  <li>GEM PATHS:
  
  <ul>
  <li>/Users/wh026399/.rvm/gems/ruby-2.2.2</li>
  <li>/Users/wh026399/.rvm/gems/ruby-2.2.2@global</li>
  </ul></li>
  </ul>
  
  <p>I was wondering what "USER INSTALLATION DIRECTORY" is. why it not point to gems under folder .rvm but .gem instead? Also, why is it using 2.2.0 which is a ruby version I didn't install?</p>