[maven-release-plugin] prepare release master-2.9.3

git-svn-id: https://source.sakaiproject.org/svn/master/branches/sakai-2.9.x-release@128719 66ffb92e-73f9-0310-93c1-f5514f145a0a
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://source.sakaiproject.org/svn/master/branches/sakai-2.9.x-release@128721 66ffb92e-73f9-0310-93c1-f5514f145a0a