allow oo-trap-user to run from non-public-key auth

BZ 1024102 - oo-trap-user does not honor requested command when SSH_ORIGINAL_COMMAND is unset
https://bugzilla.redhat.com/show_bug.cgi?id=1024102


Adding Kerberos authentication bypasses ssh authorized keys file command= replacement.
This means SSH_ORIGINAL_COMMAND is not set.
Use sys.argv when not authenticating with publickey limited commands.