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

This reverts commit c52686f8.

Fix start collector image failed

fixed docker compose image path error

Improving agent

fixed #220

1. Change dag graph layout from hierarchical to relationship
2. Change node style from square to round

Finish almost all codes about ignore, sample and analytic trace mechanism. Left analytic trace only for collector.

Create CODE_OF_CONDUCT.md

Feature/164 add operation name to be a query condition in trace page.

1. add global trace id column into segment cost index.
2. just query from segment cost index when query top segment record with condition, e.g. operation name, global trace id, cost

1. add global trace id column into segment cost index.
2. just query from segment cost index when query top segment record with condition, e.g. operation name, global trace id, cost