TII-162 Deleted sites: return true so they are marked as completed

git-svn-id: https://source.sakaiproject.org/contrib/turnitin/trunk@87029 fdecad78-55fc-0310-b1b2-d7d25cf747c9
TII-164 Fix NPE from locking code

git-svn-id: https://source.sakaiproject.org/contrib/turnitin/trunk@87030 fdecad78-55fc-0310-b1b2-d7d25cf747c9