* This is a fix for a potential security issue; the old code had edge
cases with unexpected behavior.
* LEMUR_RESTRICTED_DOMAINS is no more, instead LEMUR_WHITELISTED_DOMAINS
is a list of *allowed* domain name patterns. Per discussion in PR #600
* Domain restrictions are now checked everywhere: in domain name-like
CN (common name) values and SAN DNSNames, including raw CSR requests.
* Common name values that contain a space are exempt, since they cannot
be valid domain names.