Adding support for context paths.
Releasing FullHttpRequest after usage.

- updated to Netty 5.0.0.Alpha2-SNAPSHOT to get CorsHandler fix
- added io.netty.leakDetectionLevel=advanced to Netty server
Merge branch 'danbev-context-path-support'
initial version of the hibernate sync manager
moved persistance.xml to right location
Merge branch 'edewit-hibernate'
Extraction of versions into properties
Removing outdates RESTful server implementation.
Merge remote-tracking branch 'upstream/master'
Fixing path to diffsync branch.
Initial work of implementing differential sync.
Adding Netty snapshort repository.

Motivation:
Removes the need to build Netty locally. This will be remove when
Netty-5.0.0.Alpha2 is available in Maven central.
Adding XMPP diffsync
Initial client XMPP work
Client will send message in an explicit message param
Initial "it compiles" commit
Horrible hacking to get code working with Xmpp sync
Moving to aar packaging
Fixing message handling bugs
untangling google's registration id and diff syncs client id