This converts the initrd generation from a home grown system to dracut.
It uses the upstream modules where possible plus two specially written
dracut modules: mgainstaller and mgakadeploy.
The initrds are identical for all builds and there are lots of
bits that are incomplete and unnecesary.
e.g. copying the kernels to a folder and then not using them,
and also the module-descriptions file is not included in the
initrd itself which it should be.
We can probably customise the initrd better for different use
cases, e.g. perhaps network stuff is not needed for HD based
installs?
We may also need to install the mdraid and lvm modules for some
HD support.
This is the first attempt so I expect various bits need fixing