Method: Append default options
Method: Notify when user recive an down vote.
Method: Notify when user recive an up vote.
Method: Notify when user recive an down vote.
Method: Notify user on new reputation.
Method: Notify user on new reputation.
Method: Ajax callback for marking all notification of current user as seen.
Method: Ajax callback for loading more notifications.
Method: Ajax callback for loading user notifications dropdown.
Method: Initialize the class