Replace the ServiceXaWrapper with a simpler Synchronization implementation.  Helps pave the way for use of alternative transaction management libraries that don't work well with our XA wrapper implementations. Still DebugXaResource to go.

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1616925 13f79535-47bb-0310-9956-ffa450edef68