title: git clean isn't cleaning hidden files
body: <p>I have 3 untracked files in my working directory:</p>
  
  <pre><code>$ git sta
  ## features/subchecks...upstream/BR_4_1_4 [ahead 4]
  ?? Applications/ETM/Build/Android/.project
  ?? Applications/zFacebook/Build/Android/.project
  ?? Core/Barcode/Build/Android/.project
  </code></pre>
  
  <p>I do a dry run of <code>git clean</code> like so:</p>
  
  <pre><code>$ git clean -n
  </code></pre>
  
  <p>But it's not showing any files will be cleaned. Why is it not cleaning the <code>.project</code> files? I'm using msysgit 1.9.2 on Windows.</p>