title: Karma can't load junits plugin
body: <p>I'm trying to create a xml file that contains my karma test output. My configuration is as follows but I do not get an xml file + i get an error on some junits plugin. How do I install this?</p>
  
  <pre><code>'use strict';
  
  module.exports = function(config) {
  
    config.set({
      autoWatch : false,
      reporters: ['progress', 'junit'],
  
      frameworks: ['jasmine'],
  
      browsers : ['PhantomJS'],
  
      plugins : [
          'karma-phantomjs-launcher',
          'karma-jasmine'
      ],
        junitReporter: {
          outputFile: 'test-results-karma.xml',
          suite: ''
      }
    });
  };
  </code></pre>
  
  <p>Output in cmd</p>
  
  <pre><code>[10:50:55] Using gulpfile C:\projects\gulpfile.js
  [10:50:55] Starting 'test'...
  [10:50:56] Starting Karma server...
  WARN [reporter]: Can not load "junit", it is not registered!
    Perhaps you are missing some plugin?
  INFO [karma]: Karma v0.12.31 server started at http://localhost:9876/
  INFO [launcher]: Starting browser PhantomJS
  INFO [PhantomJS 2.0.0 (Windows 8)]: Connected on socket fsowdSE-rhiP0UWvIvdZ wit
  h id 70609702
  PhantomJS 2.0.0 (Windows 8): Executed 1 of 1 SUCCESS (0.002 secs / 0.004 secs)
  </code></pre>