vm install: enable capabilities for vm users
vm install: add a little to the root FS

We don't actually need the room for the installation, but users likely
will when they start using it.
vm install: gentler missing-params message

Instead of make failing with an error message, vm/to_rhel_vm now
politely informs you that the vm ks is being skipped if there is no
parameters.sh.
install: Clean up the Makefile a bit

No actual change to the results.
No longer echoes the sed cascade for amz.
Got rid of generic/*.repo we no longer use.
Merge pull request #369 from sosiouxme/enterprise-2.1-vm

Minor enterprise 2.1 vm improvements