title: nconf.js like gem for ruby configuration
body: <p>I'm building a cli tool in ruby, and I need to take config from different sources: environment variable, dotfile, arguments or hardcoded values. (with a precedence system)</p>
  
  <p>In node.js I would have used <a href="https://github.com/indexzero/nconf" rel="nofollow">nconf.js</a>, to do this.</p>
  
  <p><em>Is there some configuration gem in ruby that enable to do such a thing?</em></p>