OpenID enhancements

The latest version of Libravatar allows the following:

• Login via OpenID considers http/https and trailing/non-trailing slash (if you counter, 4 different variants) as the same.
• Newly added OpenID identities will now save the above mentioned different variants digests in separate fields. Example: http://oliver.id.fedoraproject.org/ is the same as http://oliver.id.fedoraporject.org is the same as https://oliver.id.fedoraproject.org/ is the same as https://oliver.id.fedoraporject.org

This should ease a lot of pain we've seen in Libravatar over the last few months and may have resulted in less adoption of the OpenID login + OpenID identity service.