* Cluster module implementation finished.

* Fix #1441 add icon files notice

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

Sync English documents to Chinese.

* Add Junit test for ribbon's NIWSServerListClassName

* Add License Head to Code file

* try to solve submodule skywalking-ui conflict

# Conflicts:
#	README_ZH.md

Init branch 6.0 for our next big iteration. Change root readme. Format field document in table.  Remove Chinese documents.

Fixed the bug of the result of GC count in query of GC trend service always 0.

* Update How-to-release.md

* Update create_source_release.sh

* Update README.md

* Update README_ZH.md

Error rate alarm is not triggered

* Update submodule skywalking-ui

* Update submodule skywalking-ui

* Update submodule skywalking-ui

* Update submodule skywalking-ui

* #1405
Add application id into service metric for the page jump from overview page to service page.

* Fixed test case error.

* Update submodule skywalking-ui

* Update submodule skywalking-ui

* Update submodule skywalking-ui

* Fixed the wrong usage of elasticsearch filter.

* #1393

The array data type of service name column are nested. Change the data type to be just a one-dimensional array.

* Update submodule skywalking-ui

* Update submodule skywalking-ui

* Prepare beta2 changelogs.

* #1207

Return true when segment parse throw exception to avoid parse the segment over and over again which read from buffer file.

* no message

* #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.

* support shardingjdbc database storage feature

* dependency and version should be defined in collector root pom.xml

* update the markdown file

* fix errors

* fix checkstyle errors

* add the Logger modifier "static" in pr #1347

* fix the issue #1376