Add more detailed story actions for maniphest.

Summary:
TransactionType gives us more information than
update, open, close, assign. We can display those in feed/notifications along with and comments on the actions.

Test Plan: did on local machine tested out.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: ddfisher, keebuhm, aran, Korvin

Differential Revision: https://secure.phabricator.com/D2683