staypuft: image size and removal, subscription fixes

* increasing image size, otherwise there's not enough space with LVM for
  mongodb to start (see https://bugzilla.redhat.com/show_bug.cgi?id=1125374)
* removing the deploy vm disks (the size change won't take effect without it)
* enable the subscription upon registration (necessary for having RHEL7 repos
  on the provisioned systems)

Change-Id: I5b892d36d45b6a060139b649dd52bda12ad1b737