Don't show client IP in push logs unless viewer can edit the repository

Summary: This locks push logs down a little bit and makes them slightly more administrative. Primarily, don't show IPs to googlebot, etc.

Test Plan: Viewed push logs as edit and non-edit users.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D7722