GUI-1150: Display a link to the create volume page if no volumes exist in the instance's availability zone in the "Attach volume to instance" dialog on the instance volumes page
GUI-1150: Remove unneeded scope variable
GUI-1150: Switch to purl.js to obtain URL param for avail zone passed from "Create new volume" link in attach volume dialog on instance volumes page.
Merge pull request #839 from eucalyptus/GUI-1150

GUI-1150: Display a link to the create volume page if no volumes exist in the instance's availability zone