Calendar tests: fix for mysql

tracim/tracim/tests/functional/test_calendar.py

         daemons.execute_in_thread('radicale', lambda: transaction.commit())
         # TODO - 20160606 - Bastien: lock should be better here ?
         time.sleep(3)  # Wait for be sure transaction commited in daemon
-
+        transaction.commit()
         try:
             event = DBSession.query(Content).filter(
                 Content.label == 'This is an event'