Merge pull request #356 in ZP/z-push from bugfix/ZP-983-handle-appointment-when-starttime to develop

* commit '6b62a009':
  ZP-983 Remove debug log.
  ZP-983 Log dates in WBXML mode and print them in the same format as they would appear in WBXML.
  ZP-983 Retrieve start/end time from MAPI if not set.
  ZP-983 Implement all cases of the specified cases of unset start/endtime.
  ZP-983 Allow MAPIProvider->setAppointment() to ignore start+endtime if they are not set.
  ZP-983 Set start and endtime to the next half hour if not set for appointments created on a mobile.
  ZP-983 Remove required flag for start & endtime in SyncObject check.

Conflicts:
	src/lib/syncobjects/syncappointment.php