* add plugin netty-socketio https://github.com/mrniko/netty-socketio
* delete create exit span interceptor.
* delete create exit span interceptor testcase.
* delete create exit span interceptor testcase.
* add constructor test unit
* change bind on random port in test case
* reverse upstream master whitespace
* resolve build_id param
* delete health check segment test case
* add ContextManager.isActive check before use activeSpan invoke
* remove unnecessary code and blank line
吴晟 Wu Sheng
mrproliu