Support pure-JTA client and server for WS-AT and REST-AT

This allows the Client and server application to just use the JTA APIs, whilst having the distribution done over WS-AT or REST-AT.

To do this we need to:

1. Remove @Transactional annotation. We then need to use some other mechanism to support the (optional) WS-AT participants that want to use annotations.
2. Client side JTA->REST-AT bridge. Needs implementing.
3. Server side REST-AT->JTA bridge. Needs integrating into code base.
4. Update the TXBridge quickstarts to use this and move them out.