Tweaked some gerrit httpd settings

[Todd Lipcon <to...@cloudera.com>]

I always have slowness issues with gerrit, so I just took a quick look at
the httpd config and noticed that KeepAlive was off. I turned it on, with a
low KeepAlive timeout, and also bumped the max number of workers (since
keepalive connections hold workers open).

Ideally we'd switch to a better server than httpd for SSL termination, but
that's more work than I have time for. Hoping that the keepalive setting
will make things a bit snappier going forward, since we'll avoid a bunch of
round trips and small TCP window sizes when fetching page assets, etc.

LMK if you hit any issues and I'll revert the change.

-Todd
-- 
Todd Lipcon
Software Engineer, Cloudera