Feature: non-blocking tracer, changed license (#57)

* refactor tracer, introduce worker to avoid un-blocker trace strategy

* fixed unit test and refactor dockerFile

* buffered events chan

* refactor yaml API core, initial web hook tracing implementations

* added banner

* changed license from GPL 3 to MIT

* Edit readme

configurations/beelzebub.yaml

@@ -4,9 +4,10 @@ core:
     debugReportCaller: false
     logDisableTimestamp: true
     logsPath: ./logs
-  tracing:
-    rabbitMQEnabled: false
-    rabbitMQURI: ""
+  tracings:
+    rabbit-mq:
+      enabled: false
+      uri: ""
   prometheus:
     path: "/metrics"
     port: ":2112"