Add a basic view count to Phame

Summary: This adds a very very basic view count to Phame, so bloggers can get some idea which posts are more popular than others. Anything more than this I think should be Facts or Google Analytics.

Test Plan: Write a new post, see post count. Reload page, post count goes up. Archive post, post count stays the same.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D18446