Updates to verions of Java/build tool/dependencies:
- Gradle 2.2.1
- Java 8
- Logging

Renamed sub-project 'rest' to 'xml' because technically it is a XML client implementation. Nu pure REST because we send the data as XML encoded en not URL encoded GET/POST data.

Changed Jersey proxy client to CXF proxy client (although Jersey is the reference implementation the CXF one integrates better with the more common logging frameworks and feels a bit more lightweight).