Fix an issue with setting tempest volume vendor_name with spaces

If the volume vendor has spaces in it, for example “Open Source”, we
need to have quotes around the uses of the variables or the behavior
will not be as expected.

Change-Id: Ie1e99b6d6de2313e5b5b5a5d3057c136c9b34601
Merge commit 'refs/changes/03/127603/4' of git://gold.eng.hq.xensource.com/git/github/openstack-dev/devstack into tmpbranch
Merge commit 'refs/changes/11/129211/1' of git://gold.eng.hq.xensource.com/git/github/openstack-dev/devstack into tmpbranch