Feed Story UI Examples.

Summary: This provides some new display methods and examples to PHUIFeedStory.

Test Plan: Tested UIExamples Page, mobile layouts, and existing Feed Pages (feed, profile, etc). I want to add a bit more but am stopping here since it's not a priority.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5749