heat-jeos.sh: Use netinst ISOs instead of full DVD isos

The netinst isos produce smaller qcow2 images and are faster
to download.  Use netinst ISOs for F17 instead.

Change-Id: I76c59728ed1b9b90b43487f93fdc2e55ee604916
Merge "heat-jeos.sh: Use netinst ISOs instead of full DVD isos"