It turns out people sometimes want to be able to change the kernel
arguments. Add a convenient API to do so for the current deployment.
This will be used by Anaconda.
OSTree is a tool for managing bootable, immutable, versioned
filesystem trees. While it takes over some of the roles of tradtional
"package managers" like dpkg and rpm, it is not a package system; nor
is it a tool for managing full disk images. Instead, it sits between
those levels, offering a blend of the advantages (and disadvantages)
of both.