xmppRoster:didReceiveRosterPush: API

Sent when a Roster Push is received as specified in Section 2.1.6 of RFC 6121.
Initialize Variable

Fixes #231
registerWithElements:error API

Fixes #232
XEP-0045: added methods to XMPPMessage category to handle room subjects, have XMPPRoom check incoming messages for room subjects and use them to set the roomSubject property
XEP-0045 Code Clean Up
Bug Fix: Message value on XMPPRoomMessageCoreDataStorageObject is not saving on CoreDate
Bug Fix: Message value on XMPPRoomMessageHybridCoreDataStorageObject is not saving on CoreDate
Merge pull request #239 from sergiosvieira/master

XMPPRoomMessage MessageStr Bugs
missing newline at end of files added
Merge pull request #241 from max-potapov/missing_newline_at_end_of_file

missing newline at end of files added
Merge remote-tracking branch 'upstream/master'