glusterd/snapshot: Recreate the mount dirs and mount the lvm snapshots on node reboot.

The lvm snapshots of the bricks are mounted at /var/run/gluster/snaps/ or
/run/gluster/snaps. These paths being on a tempfs, on reboot are removed.
So when glusterd starts, we need to recreate these paths, activate the
respective logical volumes (lvm snapshots of the bricks), and mount
these logical volumes at their respective paths.

Change-Id: Ic5ef61e79a25d9830df717c592391965fe09db62
BUG: 1061685
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/7452
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Rajesh Joseph <rjoseph@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>