Creates the test for the SocketIO extension and adds it to the boot files

[himynameschris]

[socketio-jsb] add SocketIO JS extension test, update test menu and boot files [socketio-jsb] add socket.io client library to external sources [socketio-jsb] modify test to include getTag and setTag handlers [socketio-jsb] correct on handler declarations and streamline client tagging with a map of names and sockets [socketio-jsb] correct on handler declarations and streamline client tagging with a map of names and sockets [socketio-jsb] further streamline jsb vs js codes [socketio-jsb] remove sockets[] register in favor of tag property [socketio-jsb] correct identifier

[dumganhar]

@dingpinglv Could you please review and test this PR? I think it's a great feature for JSB and html5.