Bug 1085339 - cleaning up the remote user auth configs

While our current remote-user auth plugin Apache configs are confusing there
are really only two scenarios:

1) Auth happens in Apache
2) Apache is bypassed and auth happens in Rails

Now for #2 in all cases we set the 'passthrough' environment variable instead
of sometimes setting BROKER_KEY, sometimes passthrough and sometimes
local_traffic.

This makes the configuration much more readable.  I picked the passthrough
variable since that was the most backwards compatible for OpenShift Enterprise
perspective.  Also, oo-accept-broker's check was a little stale so I fixed that
too.