CAL-834 Restore the keys for Save and Cancel buttons

Restore the keys wrongly deleted in CAL-658:
* Participant Invitation
* Import/Export form
* Share Calendar
CAL-801 js send request to much when drag drop event

Fix description:
- catch only PathNotFoundException
- use off('mousedown') method before adding new on('mousedown')
CAL-529 Fixed resizing event in week and day view

Fix description: Fix resizing event in javascript of week view and day view.
CAL-787 CLONE - Not show warning message, or show event on working pane if event is repeated by past time

Fix description: Show warning message if event is repeated by past time.
Merge commit 'f4609187e148912ee49330bc89289dc3f1a122e0' into HEAD