Limit specs in ipolicy command lines are always complete

Command line options are brought in line with the specs change of previous
patch. Old options are still allowed in gnt-cluster init, where the
semantic will remain non-ambiguous even after introducing multiple specs.

Signed-off-by: Bernardo Dal Seno <bdalseno@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>