Add backup / restore admin commands

[thebentern]

No description provided.

[ianmcorvidae]

A couple small things, mostly seems good to me though

[ianmcorvidae]

It might be nice if we allow people to pass FLASH and SD here. I think we could do that by trying to parse as an int, and if it fails, throw it at something like admin_pb2.AdminMessage.BackupLocation.__getattr__('FLASH') to convert.

I think this could be done by adding a helper function and passing it as type to these add_argument calls:

def backup_location(string):
    try:
        return int(string)
    except ValueError:
        return admin_pb2.AdminMessage.BackupLocation.__getattr__(string)

I'm a bit tired so hopefully I'm relaying this properly, heh.

[ianmcorvidae]

You probably want default to stay None (that's what's passed if the argument isn't passed on the command line at all) and to set the admin_pb2.<...> value as const (which is what's passed if the argument is passed bare, without a real value).