Oracle JDK 8 compatibility

The SOS compiles under Oracle JDK 8 (see #7).

ae7b445 is somehow hackish: the service loader file for SAXON is malformed to comply with bugs in Java 1.5, and the newer, fixed versions of SAXON would introduce additional 5MB. 

It think, that is a bit much for using some XPaths in the GDA operation, so I've overwritten the file in the GDA module, but the solution is quite unreliable, because it only overrides the original file because our Jar is loaded first, which will break with different class loaders, etc.

I've also activated Java 8 on Travis CI, and the build now passes.