Conpherence - refactor display classes a bit

Summary:
D12409 made me realize this was a bit janky. PhabricatorTransactionView was only being used by Conpherence, so move and rename that class to ConpherenceTransactionView. Also, rename the existing ConpherenceTransactionView to ConpherenceTransactionRenderer, moving the actual view bits into the new ConpherenceTransactionView. Resulting code is a bit cleaner IMO.

Diff 1 of 2 (second diff has to be written. =D). Diff 2 will take care of the CSS and possibly clean things up further.

Test Plan: played around in conpherence full and conpherence column and things looked nice

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D12410