title: how to add gem dependency with :path and :branch
body: <p>I am working on a rails gem that has dependency on the following</p>
  
  <p><code>gem 'authlogic', :git =&gt; 'git://github.com/odorcicd/authlogic.git', :branch =&gt; 'rails3'</code></p>
  
  <p>How can I add this in the gem spec as a dependency? Specifically I need to specifiy the path and branch in the dependency.</p>