Allow repository push logs to be filtered by pusher and repository

Summary: Ref T4195. Add UI options to filter push logs by pusher and repository. Add a link from the repository view page to the push logs.

Test Plan: Viewed a hosted repository, clicked logs link, saw logs. Filtered lgos by repo/pusher.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4195

Differential Revision: https://secure.phabricator.com/D7713