Tool to test ssh authorized_keys files

Users can check that their ~/.ssh/authorized_keys files is "acceptable" with /usr/groups/admin/cmds/check-ssh-auth.pl.

The script, which is used to check the acceptability of users' authorized_keys, has been modified to be (a bit) more user friendly, having originally been intended for scanning all user files, rather than for a user to test their own file. With no arguments it reports things which need fixing. With a "--warn" flag it warns of "acceptable" keys as well.

It's being tuned, so any feedback is welcome.