* update 5.x grpc version form 1.10 to 1.14 and  Solve the resulting guava and log4j version conflicts

* Specify guava version 20.0

* update parrent pom guava version

* Moves to Maven wrapper to stabilize the version in use

This will ensure those building will have similar experience due to
having a fixed maven version.

* Updates most plugin versions and removes redundant configuration

* Sets up build enforcement for JDK 1.8 until further work occurs

* Change version 

* [maven-release-plugin] prepare release apm-5.0.0-alpha

* [maven-release-plugin] prepare for next development iteration

Fix assmbly for mvn clean install -Papache-release and update version to SNAPSHOT for SNAPSHOT release.

2. Change the http servlet worker from local asynchronous call to local synchronous call.

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

2.Release the prototype of ‘TraceSegment’.