Remove <Unknown> entry from Authentication Status box.

Remove <Unknown> entry from Authentication Status box, these entries were for keypairs(AuthKeyPairAmazon), and had null in authtype field in the table.

https://bugzilla.redhat.com/show_bug.cgi?id=1158180
https://bugzilla.redhat.com/show_bug.cgi?id=1158179

@fryguy @dclarizio please review.
You may still want this else in case something gets added in the future that isn't known?