Clean up URIs in Phame

Summary: Normalize "getViewURI" and "getLiveURI" for PhameBlog and PhamePost. Use pretty URIs in PhamePost

Test Plan: View Recent, View posts, edit post, new post, move post, view live.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D14713