3PAR driver add missing domain check on QOS cmd

The 3PAR drivers need to support CPGs that are not part of a
virtual domain on the 3PAR backend. This patch now checks
if the domain is set before calling the createvvset command.
This instance was overlooked in the following patch that has
already been merged: https://review.openstack.org/#/c/42697/

Also fixes: bug 1212328

Change-Id: I0375dfc89104775582b9258f18f97c683e6148b1
Dont crash service if sf cluster isnt available

Currently if the SolidFire driver is configured but the cluster
isn't available for some reason the ensure_export call will raise
an unhandled exception and crash the volume-service.

We should be able to handle things like loosing connectivity to
a single back-end without impacting the other volume-service
backends.

We'll wrap the ensure_export call in a try block here and
return None in the case that the connection can't be made.
This will keep the service from crashing and log an error
message that the connection timed out.

Additional work would include adding a periodic retry task
to the manager to try and start the backend service for us
on some regular interval incase the device comes back.

Fixes: bug 1215064

Change-Id: Ice3f517d220c40113074bb77adbb10d5e32abd0b
Merge "Dont crash service if sf cluster isnt available"
Merge "3PAR driver add missing domain check on QOS cmd"