Initial attempt
Base packages on Fedora Server product instead of Fedora Cloud

- in part because most VMs should now be PVHVM, and/or should be
  portable to other platforms
- accept that NetworkManager will be installed by default
Adopt some conventions from Fedora's `spin-kickstarts`

- Disable in-memory /tmp
- Remove yum repo data and import the RPM GPG key
- See https://git.fedorahosted.org/cgit/spin-kickstarts.git/tree/fedora-cloud-base.ks?h=f21
Try to avoid the hardware-support package, which is unnecessary.
Remove really unneeded hardware support files
Update README with correct links

- no difference between PVHVM and PV kickstart script, so collapsed to
  same filename
Merge branch 'feature/fedora-21' into develop