Adding sync-token back to the ics generator.
Several issues fixed in the migration process.

Fixes #566
Prepping for a release.
Fixed the second issue from #566.
Switched to new api for creating request objects.
 Freebusy was throwing an error when targetting accounts that have no calendars. Fixes #567
Merge branch '2.1'

Conflicts:
	ChangeLog.md
	lib/DAV/Version.php