Relax SAN DNSname validation and constraints to permit non leading *

Relax SAN DNSname validation and constraints to permit non leading *
wildcards. While we may choose not to support them the standards
appear to permit them optionally so we can't declare a certificate
containing them invalid. Noticed by jeremy@, and Steffan Ulrich
and others. Modify the regression tests to test these cases and
not check the SAN DNSnames as "hostnames" anymore (which don't support
wildcards).

ok jsing@, tb@