title: Prevent git from writing empty merge commits
body: <p>Accustomed to SVN, I always do an 'update' before sharing any changes, so before making any pushes I always pull first.</p>
  
  <p>It's annoying when I pull (even though there weren't any changes to the remote) and see a commit for a merge with <code>0 changed files with 0 additions and 0 deletions</code>.  Commits like:<br>
  <a href="https://github.com/UCF/Harvard-Mobile-Web/commit/be9d6b2d1ab196554e080d8b8647a9d16c8a5ddf" rel="noreferrer">https://github.com/UCF/Harvard-Mobile-Web/commit/be9d6b2d1ab196554e080d8b8647a9d16c8a5ddf</a>  </p>
  
  <p>I find this to be useless noise when looking at the commit history.</p>
  
  <p>Maybe there's something I'm missing, is there any point to this commit?  If not, is there any way to prevent git from writing empty merge commits?</p>