* notification for indexer * use NullNotifier as parent struct
* mail notification implement interface * fix file comment year * use NullNotifier as parent struct of notifiers
* add notification interface and refactor UI notifications * add missing methods on notification interface and notifiy only issue status really changed * implement NotifyPullRequestReview for ui notification
* Notification - Step 1 * Add copyright headers * Cache issue and repository on notification model
Lunny Xiao
Andrey Nering