Make AphrontRequest::getHost() work properly in the presence of a port

Summary: This currently gives us back "domain.com:port" if there's a port, which messes up the new Phame logic. Make getHost() do what one would reasonably expect it to.

Test Plan: Loaded my local, which is on 8080.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D3571