Update index.js

I have added some piece of code to specify the transport type in arguments. It will be useful to do the benchmark with primus and engine.io (or other)..
Update benchmark.js

add the transport type in fork call..
Update primusworker.js
Update README.md
Update README.md
Merge branch 'patch-2' of https://github.com/phpbala/websocket-bench
Merge branch 'patch-3' of https://github.com/phpbala/websocket-bench
Merge branch 'patch-4' of https://github.com/phpbala/websocket-bench
merge phpbala PR