Fix issues with Java Spalloc Client

[rowleya]

The spalloc client in Java SpiNNMan doesn't seem to be working... check out why!

[Christian-B]

Do we still need it?

[rowleya]

This could be used by the NMPI service instead of relying on the old spalloc compatibility service. It has that option, but it seems the option is currently broken. This then means that we fall back on the old spalloc compatibility service, which is clunky and often results in jobs not being released properly (it seems to disconnect and reconnect randomly).

I think the NMPI server code had some issue where you needed a user token to speak to the NMPI job server (not run by us); this may still be the case in which case this will not be fixable anyway! I will suggest (probably to myself) to look at this first before fixing in case it isn't worth it...