title: Ember : downgrading ember with bower install
body: <p>I've been switching to the 1.13.2 version of ember on a git branch, and now I want to come back to 1.11.1 when going back to an other branch.</p>
  
  <p>I've been running <code>npm install</code> and <code>bower install</code> without failure.</p>
  
  <p>But when I run <code>ember server</code> I run into the following error :</p>
  
  <pre><code>Missing bower packages: 
  Package: ember
    * Specified: 1.11.1
    * Installed: 1.13.2
  
  Run `bower install` to install missing dependencies.
  </code></pre>
  
  <p>Running <code>bower install</code> again does not solve the problem, neither does <code>bower cache clean</code>.</p>