For Fedora, use a boot partition so that we can benefit from a
root partition using ext4
Don't install NetworkManager on Fedora
Extend Fedora post-install script significantly

- basic logging to `/root/ks-post.log`; extended debug logging to
  `/root/ks-post.debug.log`
- turn on generalized networking and use a generic localhost hostname
- remove linux-firmware package (unneeded on PV)
- remove SSH host keys
Fix logging on CentOS 7 kickstart

- Previously, stdout/stderr output of script would mess up the log
- Now those are redirected to a more verbose `/root/ks-post.debug.log`