[OBMFULL-5693] - No timezone information is emitted by resource calendars

Conflicts:
	java/sync/icalendar/src/main/java/org/obm/icalendar/Ical4jHelper.java
	java/sync/services/src/test/java/org/obm/sync/resource/ResourceServletTest.java
	java/sync/services/src/test/java/org/obm/sync/server/mailer/EventChangeMailerTest.java