OO-538: add some commit before sending an event via JMS (JMS can work the event in a separate thread before the producer commit its changes on the database)

OO-438: fix an empty  select ... in () in the query to update the subscribers if there isn't subscribers to update

OO-373: made the notifications manager robust under concurrent access, write more unit tests to tests the queries on the database and test it under concurrent load

OO-213: make OpenOLAT more robust against corrupted course, mark them in details view, make home resistant to corrupted courses, give the possibility to delete them

FXOLAT-296	: enhanced REST API for notifications (by type), better unit tests this function, optimize the way to get notifications by type in the controller

--HG--
branch : bps