Ported parameter setting UI from benchmark.html to xhr_benchmark.html
Ported parameter setting UI from benchmark.html to xhr_benchmark.html

Enable to run the bench multiple times and display stddev.
Added 'batch' button that runs send and receive benchmarks.
Support turning off data verification.

R=tyoshino@chromium.org

Review URL: https://codereview.appspot.com/137980043
GoogleChromeLabs/pywebsocket3,google/pywebsocket,google/pywebsocket,googlearchive/pywebsocket,google/pywebsocket,GoogleChromeLabs/pywebsocket3,googlearchive/pywebsocket,GoogleChromeLabs/pywebsocket3,googlearchive/pywebsocket