Override getLocalPathBase in GlusterFSConnection

Override getLocalPathBase in GlusterFSConnection as a better
way to specify mount point for GlusterSD

Change-Id: I8d7d0980b0a863f8d47d61936b2d8fdab71a6a0c
Signed-off-by: Deepak C Shetty <deepakcs@linux.vnet.ibm.com>
Reviewed-on: http://gerrit.ovirt.org/12127
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>