Add notification to toolbar
Add AppNotification service to dismiss notification

- Rename version-notifications to appNotification to prevent confusion with IRC notifications
- Sync toolbar's $scope.appNotification with $rootScope.appNotification in $rootScope.$watch
Implement fetchUpdate()

Use GitHub Events API to find the most recent PushEvent to the branch gh-pages. Then check the SHA of the commit against $rootScope.meta.version. If the hashes differ, set the appNotification.
Merge pull request #63 from coldstorm/version-notifications

Version notifications