* 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

* Change version 

* #1202

1. Determine the log is enabled for the DEBUG level before printing message.
2. Make the columns initialize to be static attribute.
3. Topology build optimize: Cache query result to avoid repeating queries.

* #1202

Add elasticsearch batch process setting into application.yml.

* #1202

Fixed check style error.

* #1202

Use XContentFactory to build source to insert into elasticsearch.

* Add Zipkin receiver

* add the Logger modifier "static" in pr 

* support shardingjdbc database storage feature

* Fixed #1090

1. Move setting the performance from create table action to install action.
2. Add check step that avoid filed type not match the definition when project upgraded.

* Setting namespace by class construct.

* Replaced ObjectUtils for Objects methods

* Refactor the collector configuration initialization.

#1047

* 1. Add the performance collection point.
2. Report formatter.

#1032

* Add a new cache implementation by caffeine.

#1032

* Performance optimization:
Make all the loggers class variable to have the static modifier.

#1009

* Add client side token.

* Fix ci.

* Fix most codes of token auth at both sides.

* Add settings in config files.

* Make auth interceptor doesn't throw expcetion.

* Update AuthenticationSimpleChecker.java

* Update AuthenticationActivator.java

* Revert "Update AuthenticationActivator.java"

This reverts commit 0935f18fd6802ab84c12e0609c21ef753ff51be3.

* Merge branch 'feature/token-auth' of https://github.com/apache/incubator-skywalking into feature/token-auth

# Conflicts:
#	apm-collector/apm-collector-agent/agent-grpc/agent-grpc-provider/src/main/java/org/apache/skywalking/apm/collector/agent/grpc/provider/AuthenticationSimpleChecker.java

* Fix Auhentication token works incorrect (#1001)

* Fix Auhentication token works incorrect

* Change way to build GRPC Channel

* Response an empty header when auth fails.

* Finish the prototype of TLS of gRPC between agent and server.

* Fix for rat check.

* Update GRPCChannelManager.java

* Update AgentModuleGRPCProvider.java

* Upgrade netty version (#971)

* Make sure end user can't start gRPC server with and without SSL in the same port.

* Proposal the code structure for table name prefix. Related to #932

* Fix style check.

* Keep ESDao table name in control.

* Finish all codes about ES namespace feature.

* [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. Delete the history data before the setting that you can find the property name of history_delete_before_days in the application.yml file.