Recommit of 'Faster response body verification in XHR text receive benchmark'

This fixes the performance bottleneck of XHR text receive benchmarking.

R=tyoshino@chromium.org

Review URL: https://codereview.appspot.com/132250043

git-svn-id: http://pywebsocket.googlecode.com/svn/trunk@827 4ff78f4a-9131-11de-b045-6380ec9940d4
Introduce UI for changing benchmark configuration

Also merges parameter and config

R=ricea@chromium.org

Review URL: https://codereview.appspot.com/123790044

git-svn-id: http://pywebsocket.googlecode.com/svn/trunk@828 4ff78f4a-9131-11de-b045-6380ec9940d4