deploy: Propertly append multiple kernel arguments with --karg-proc-cmdline

We want to allow multiply specified arguments, as it's useful for
things like console= and rd.lvm.lv.

See: https://bugzilla.gnome.org/show_bug.cgi?id=721136

Reported-by: Dusty Mabe <dustymabe@gmail.com>
packaging: Make the ostree rpm own and create /etc/ostree/remotes.d/