OF-843: Update Hazelcast plugin

Updates include changes for Openfire Session API, plus changes needed to
upgrade to Hazelcast 3.3.1; also some core housekeeping (NPE)
OF-421: Resolve merge conflicts

Updated ConnectionManagerImpl and related to merge recent changes
related to client connection throttling (MaxReadBufferSize)
Merge branch 'aberenguel-of-421-mina2'
Merge branch 'master' of https://github.com/igniterealtime/Openfire
OF-421: Update xmldebugger for Mina API changes

Adjust xmldebugger for changes in the MINA 2.0.7 filtering API
Merge pull request #86 from tevans/master

OF-843: Update Hazelcast plugin