Modernize user activity logs (ApplicationSearch, policies)
To support this, implement modern policies and application search.
I also removed the "old" and "new" columns from this output, since they had limited utility and revealed email addresses to administrators for some actions. We don't let administrators access email addresses from other UIs, and the value of doing so here seems very small.
Test Plan: Used interface to issue a bunch of queries against user logs, got reasonable/expected results.
Reviewed By: btrahan
Subscribers: keir, epriestley
Differential Revision: https://secure.phabricator.com/D8856