Add sample systemd service descriptors for RHQ

Sample systemd service descriptors that work with RHQ 4.14 (and with potential 4.13.1), support start & stop & status correctly.
Yes, I was just trying to search for some value to edit. The real value would of course look like for example in my dev-system:

[Service]
ExecStart=/home/miburman/projects/rhq/dev-container/rhq-server/bin/rhqctl console --server