Add Comments for Notification::addNotifications().

Signed-off-by: Dhananjay Nakrani <dhananjaynakrani@gmail.com>
Add notifcation fixture.

Signed-off-by: Dhananjay Nakrani <dhananjaynakrani@gmail.com>
Add Test Cases for Notification Model.

Signed-off-by: Dhananjay Nakrani <dhananjaynakrani@gmail.com>