bin/admin: Don't require root for instutil
bin/admin: Don't require root for instutil

Otherwise, we can't even do `--help` on it. The subcommands all already
have the root flag set.

Closes: #1126
Approved by: cgwalters

GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree