TII-161 Code clean, merge r87012-87013 from trunk

git-svn-id: https://source.sakaiproject.org/contrib/turnitin/branches/sakai-10.x@87028 fdecad78-55fc-0310-b1b2-d7d25cf747c9
TII-162 Deleted site handling: r87029 from trunk

git-svn-id: https://source.sakaiproject.org/contrib/turnitin/branches/sakai-10.x@87031 fdecad78-55fc-0310-b1b2-d7d25cf747c9
TII-164 NPE from locking code: r87030 from trunk

git-svn-id: https://source.sakaiproject.org/contrib/turnitin/branches/sakai-10.x@87032 fdecad78-55fc-0310-b1b2-d7d25cf747c9