Project watchers watch all issues and postings
Update watch doc
Fixed broken test
Send Notifcation for new posting.

Remove duplicated code with the notifcation for new comment.
Send notification for new issue.

Remove duplicated code with the notifcation for new posting.
Send notification for updating issue.
Send notification for mass-update.
Send notification to mentioned users.

For users mentioned in new issue, new comment and new posting.
Introduce scheduled notification by Akka.
Apply scheduled notification for new issue.
Apply scheduled notification for new posting
Apply scheduled notification for changing assignee.
Apply scheduled notification for changing state.
Show notifications on the Site Main.
Add some javadoc for notification.
notification: Refactor Global.

Move Global.scheduleNotificationByMail() to NotificationMail.startsSchedule().
notification: Extract string formatting to methods.

Add formatReplyTitle and formatNewTitle.
notification: fix minor typo. s/프로젝틑/프로젝트를/
notification: Extract some codes adding notification.

To addNotificationFromNewPost and addNotificationFromNewComment.
issue: Replace IssueApp.isAssigneeChanged.

With Issue.assigneeEquals.