supervdsmServer: Run sourceRouteThread in a thread

The current code was running the sourceRouteThread main function in the
main thread instead of starting it in a thread. This probably leads to
bogus message in the supervdsm log. Now the code is doing what it was
trying to do.

Change-Id: I5eb78b57b9ae6ada9948815020ac3d5ac005d20a
Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/22718
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Ayal Baron <abaron@redhat.com>
Reviewed-by: Assaf Muller <amuller@redhat.com>
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>