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.
Similar to qubes-update, it will save then verify the hashes of
the kexec files. Once TOTP is verified, a normal boot will verify
that the file hashes and all the kexec params match and if
successful, boot directly to OS.
Also added a config option to require hash verification for
non-recovery boots, failing to recovery not met.
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
