Make IQN validator abide by RFC3271

Make valid.IQN judiciously follow the RFC

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1031891

Change-Id: I4bb891377f5238530dc5b2446eb684b05469cc8c
Signed-off-by: Ryan Barry <rbarry@redhat.com>