Fix issue that skywalking-agent.jar include the google class  and exclude the proto files inside protobuf-java

1. Remove the “apm-trace” module, isolate the trace structure between agent and collector for considering performance.
2. Change the head name.
3. Provide potienal mechanism for ignore trace with certain suffix.

Fix compile issue. Add new rest-service Object: SegmentsMessage.java. It uses Gson(JsonAdapter) as serialize/deserialize tool.