Fix issue #178

This change allows a lock timout header to have multiple values, per RFC 4918 section 10.7.
All but the first value are ignored.
Unittests should be OK again.
Merge pull request #395 from risacher/lock-timeout

Fix issue #178
Updated changelog.
Unittest for Issue #178, #395.
Fixed Issue #382.
Merge remote-tracking branch 'origin/master' into calendar-auto-schedule

Conflicts:
	lib/Sabre/CalDAV/Plugin.php