don't create a cinder type if already it exist

Avoid Puppet warnings by checking if a volume type exist before trying
to actually create it.

Closes-bug #1319857
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>

Change-Id: Ib31db545d1d761fc6abed0a42dd7ae8e6cc0f25f
cinder-type: delete PATH in exec

By deleting PATH, we are able to run both commands (cinder type-* and
grep) without environment issue.

Change-Id: I5dd1c60892c7848b02ab71ea30bc49b4b4c26029
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>