So change coverage tools from Cobertura to JaCoCo

Fix an out-of-date package name.

Exclude the grpc generated codes for ci coverage.

Add “checkStyle.xml” and “codeStyle.xml” files, varify the code-style when “mvn compile” and CI. This is the initialized commit.

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

Remove collector dependency from agent-module. We will use HTTP-restful-service. Remove unnecessary dependencies/shades on collector and agent sides. Fix CI issue.

2.Release the prototype of ‘TraceSegment’.