Add 15-dracut-fedora.conf, drop related patches
Rather than patch osbuilder dracut files, drop in our own dracut
conf file with Fedora specific additions.
Rework the way we generate modules-load.d conf files in osbuilder.sh
to handle this in a nicer way, which also has the benefit of ensuring
modules-load.d doesn't fail if we specify a non-modularized driver
Signed-off-by: Cole Robinson <crobinso@redhat.com>