[Benchmarking] Limit access to benchmark web servers

[Schlagel, Joel D. IWR]

I think we should update the httpd.conf to limit access to the web server to
ip ranges for those directly working on the benchmark servers.  When running
the final benchmarks we could deny from all but the test server.  After the
final results are in - we can re-open the servers for wider access.

   -joel