OO-540: send e-mail after removing a member of a course, use the changed content of the E-mail while adding a new member to a course

OO-538: unify our implementation to retrieve entity managers with spring, remove wrapper classes to acesss directly transaction and entity manager, don't cache them anymore in our code, @Transactional fully functional, add some sleep in unit tests to wait from the new asynchronous multi user events

OO-449: fix an issue with roseter entry being locked after restart, reuse the EntityManager created by Spring if one available...

OO-531: make the FlexiTable more flexi, doesn't redraw all the table but only a component within, more work on autocompleter

OO-530,OO-537: as follow-up of the work in 8.3, remove some maps which are not really useful, remove more unused variables, remove the views and their mapping...

OO-530: replace HashMap with ConcurrentHashMap in some critical places where multi threading is an issue

OO-524: split and wrap the panel to make 2 different and independent forms, the OK button isn't highlighted anymore after selecting "home" or "contact"