sanlock: support for Gluster domains

sanlock lease creation and domain monitoring didn't work
on domains using glusterfs.
Now the right paths for glusterfs domains are used.

Change-Id: I723604e67906abfe2c7618821911cdf43f133a58
Bug-Url: https://bugzilla.redhat.com/1023962
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>