admin: Add --no-bootloader option to update-kernel
admin: Add --no-bootloader option to update-kernel

Will be used by the QA scripts, since we need to inspect the kernel
configuration and generate a correct grub conf from that, rather than
trying to have update-bootloader reuse an existing config, since there
won't be one initially.

sujitfulse/ostree,leandrosansilva/ostree,leandrosansilva/ostree,leandrosansilva/ostree,gatispaeglis/ostree,GNOME/ostree,sujitfulse/ostree,resin-io/ostree,sujitfulse/ostree,leandrosansilva/ostree,sujitfulse/ostree,gatispaeglis/ostree,sujitfulse/ostree,GNOME/ostree,leandrosansilva/ostree,resin-io/ostree,gatispaeglis/ostree,gatispaeglis/ostree,GNOME/ostree,gatispaeglis/ostree,GNOME/ostree,gatispaeglis/ostree,resin-io/ostree,GNOME/ostree,resin-io/ostree,resin-io/ostree