Check for non-default volume name template.

The iscsi delete methods in iscsi.py had hard-coded volume names
'volume-%s'.

If a user configured volume_name_template to
something other than default the result is failure to remove
the iscsi_target.

volume create worked appropriately and created the correct name
in the DB, so the persistence files were the only thing affected
or named incorrectly.

Fixes bug: 1101071

Change-Id: Id5575874b2cebd9b3509d739cb92abf06c503c4e
Merge "Check for non-default volume name template."