include angular-raven module for plugins

I created an Angular.js module for Raven.js and thought it might be great to include it as a plugin for core

Here is an example using the latest Angular
````html
<body ng-app="YOUR_APP" ng-controller="MainCtrl">
  <a href="#error" ng-click="logError()">Log Error</a>
</body>
<script src="http://cdnjs.cloudflare.com/ajax/libs/raven.js/1.0.8/raven.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.2.0/angular.js"></script>
<script>
  Raven.config('YOUR_PUBLIC_DSN', {
      // Raven settings
    })
    .setUser({
      "id": "SERVER_RENDERED_ID",
      "email": "SERVER_RENDERED_EMAIL"
    })
    .install()
<script>
<script src="app/bower_components/angular-raven/angular-raven.js"></script>

<script>
  angular.module('YOUR_APP', [
    'ngRaven',
    'controllers'
  ])
  .config(function(RavenProvider) {
    // There is a development flag to log errors rather than sending it to Sentry
    RavenProvider.development(true);
  });

  angular.module('controllers', [])
    .controller('MainCtrl', function($scope, Raven) {
      $scope.logError = function() {
        Raven.captureMessage('Error');
      };
    });
</script>

````