title: Custom Rails authentication / authorization
body: <p>I know questions of this kind <a href="https://stackoverflow.com/questions/24298/best-solution-for-authentication-in-ruby-on-rails">have</a> <a href="https://stackoverflow.com/questions/13254/open-id-authentication-in-ruby-on-rails">been</a> <a href="https://stackoverflow.com/questions/38901/strange-rails-authentication-issue">asked</a> before, but my situation differs a little.</p>
  
  <p>On my rails app I have to validate the user login against an existing repository and then control authorization to given modules. So, I don't want the solution I go for to generate a model for my users and rely on that. The authetication per se needs to be customized.</p>
  
  <p>Under that scenario, what would be the best plugin to use?</p>