OBMFULL-5152 Add Server-Side Anonymization of Events Synchronized

Conflicts:
	java/sync/common/src/main/java/org/obm/sync/calendar/Event.java
	java/sync/common/src/test/java/org/obm/sync/calendar/CalendarItemsParserTest.java
	java/sync/common/src/test/java/org/obm/sync/calendar/EventTest.java