Allow PhameBlog to take a full URI instead of just a domain name

Summary: Ref T9897. This moves "Domain" to "DomainFullURI" to allow setting of https or for some reason, a port. I guess.

Test Plan: Try to break by setting a path, or fake protocol. Set to http, or https, see correct redirects. Verify domain still gets written.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9897

Differential Revision: https://secure.phabricator.com/D16173