* Cluster module implementation finished.

* Fix #1441 add icon files notice

* Amend notice file, add excluding icon folder in rat config

Update and nail org.apache.skywalking/apm-checkstyle version to a release version, 5.0.0-beta for now. (#1270)

* Update pom.xml

Add developer email address.

* Update pom.xml

* Update pom.xml

* Delete pom.xml.versionsBackup

* Delete pom.xml.versionsBackup

* Update pom.xml

* Delete pom.xml.versionsBackup

* Update pom.xml

* Upload more dependencies.

* Add all UI licenses to license file.

* fix ui

Fix IPMC checks for releasing.

* Update docs for alpha release

* Delete a comma.

* Update How-to-build.md

* Add data-set licenses file

* Rename LICENSES-data-set to LICENSE-data-set

* Update LICENSE

* Remove fastclick from LICENSE

* Make the git submodule command to be a maven profile plugin. Let this command not execute by default install command.

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

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

* Product name is not correct

* Add more documents for release.

* Change profile id.

* Add CHANGES file in distribution file.

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

This reverts commit ac815019.

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

This reverts commit 095597c9.

* Add rat plugin to check dependency license and add license head into missing files.

* Fix docs.

* Exclude web ui config file.

* Next release guide.

* UI update.

* Update docs.

* Build source shell.

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

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

* Add more dependency licenses.

* Change the asm component’s license.

* Create style check module.

* Add scm, licenses, mailing lists into root pom.

* Add jacoco and coveralls maven plugin into check style module’s pom.

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

Fixing javadoc. And try to trigger a ci fail in this commit, in order to make sure javadoc will be checked in further pull request.

Remove OJDBC and resin artifacts from ci-dependencies driectory as they as not Apache license compatible.
The user can onetime manually download them, and the maven reactor will automatically build the corresponding plugins.

OJDBC is OTN which requires a user click-through agreement.
Resin is GPLv3, meaning any derivative work must also be GPLv3 licensed.
https://www.apache.org/licenses/GPL-compatibility.html

ref: https://github.com/apache/incubator-skywalking/pull/737

Move `apm-network` module under the new root module `apm-protocol`. And add `apm-ui-query` under the `apm-protocol` module.

Do not use the propertie for checkstyle header file path that lead to the checkstyle plugin of IntelliJ idea not work.