Transactions - make the details stuff generic and ajaxy

Summary: Fixes T2213

Test Plan: Updated a pholio mock description. Observed that when I first showed details there was a round trip made. Toggled show / hide noting no more trips made to server.

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, aran

Maniphest Tasks: T2213

Differential Revision: https://secure.phabricator.com/D6801