Give PHUITwoColumnView an addPropertySection method
Summary: Simplifies building pages a little more, adds a helper method to just add a property section to the main column automatically above other content.
Test Plan: Review Ponder, Herald, Passphrase, Countdown.
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin
Differential Revision: https://secure.phabricator.com/D15377