Changed the checking of required hashes or required rollback state
to be right before boot, allowing the user to sign/set defaults
in interactive mode.
Also cleaned up usages of recovery and fixed iso parameter
regression.
Refactored boot parsing code and applied that in local-init to
scan /boot for grub options and allow the user to unsafely boot
anything. This goes a long way to addressing #196.
Optionally the user can customize those boot parameters or enforce
arbitrary hashes on the boot device by creating and signing config
files in /boot/ or /media/ or /media/kexec_iso/ISO_FILENAME/.
Supports booting from USB media using either the root device or
a signed ISO as the boot device. Boot options are parsed with
quick/dirty shell scripts to infer kexec params.
Closes#195 and begins to address #196
