Mahara mobile WS syncing notifications fails to sync 'ALL' notifications( e.g. user to user)

[Alexey Omelchenko]

Related to #1656151.

function get_notifications in module_mobileapi_sync.php file uses following query to get notifications:
SELECT n.id, n.subject, n.message FROM {notification_internal_activity} n INNER JOIN {activity_type} a ON n.type=a.id WHERE FLOOR(EXTRACT(EPOCH FROM ctime AT TIME ZONE CURRENT_SETTING('TIMEZONE'))) BETWEEN ? AND ? AND n.usr= ? AND n.read = 0.

Query doesn't include notifications from user to user ...