SockJs Sample client

Current sample has test http server based on node.js and test page available by URL:
html http://localhost:9999/web_client.html

Only one transport is supported: xhr_streaming, but generally it shows, how SockJs interact with client.

1. install nodejs from nodejs.org
2. execute npm install in sockjs_test_server directory
3. open one more terminal window and execute node ./server withing sockjs_test_server dir
4. in sockjs-python execute python ./main.py