glusterd: log changes in volume create and delete codepath

Making log changes involving two commands as they both share sections
of code (like the part where the volume metadata is cleaned up in vol
delete in case of success; and in vol create in case of failure).

* Most of the changes are of the 's/THIS/this' kind.

* Changed some of the log messages to give as much information as
  available in case of failure.

* Changed log levels in some of the log messages.

Change-Id: I10242511fe9400a07ab04717464d748d9172dd85
BUG: 812356
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/4462
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>