title: Excluding files from coverage when using Karma and Istanbul
body: <p>I am using Karma to test my JavaScript and get coverage reports.  I am using the Istanbul coverage report, which is the default.  Here is my preprocessors parameter:</p>
  
  <pre><code>    preprocessors: {
          'framework/**/*.js':'coverage',            
          'framework/*.js':'coverage',
          '!framework/node/**/*.js':'coverage',         
          '!framework/test/**/*.js':'coverage',                                 
          'framework-lib/**/*.js':'coverage',
          '!framework-lib/tool-data-api/tool-data-api.js':'coverage'
      }
  </code></pre>
  
  <p>As you can see, I am trying to use the "!" as a negate command, which usually works with Node.  However, it is not working here and none of my directories are being excluded.</p>
  
  <p>Is there any way to do what I am trying to accomplish?</p>