title: Exclude a folder from main-bower-files
body: <p>How do I filter out an entire folder from the <a href="https://github.com/ck86/main-bower-files" rel="nofollow">main-bower-files</a>?</p>
  
  <p>For example, if I'm doing this <code>mainBowerFiles('**/jquery-validation/**')</code>, it returns only the files from the <code>jquery-validation</code> folder, but I need the opposite.</p>
  
  <p>I've tried <code>mainBowerFiles('!**/jquery-validation/**')</code>, however it seems like <code>!</code> sign doesn't work in this case. What's wrong with my pattern?</p>