R1:5ca84589bdf6

Add an SSH access log

Summary: Ref T4107. Ref T4189. This implements an SSH access log, similar to the HTTP access log.

Test Plan:
[Thu, 05 Dec 2013 13:45:41 -0800] 77841 orbital ::1 dweller epriestley epriestley git-receive-pack /diffusion/POEMS/ 0 324765 402 232
[Thu, 05 Dec 2013 13:45:48 -0800] 77860 orbital ::1 dweller epriestley epriestley git-receive-pack /diffusion/POEMS/ 0 325634 402 232

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4107, T4189

Differential Revision…