* Sample operator code.

* Indicator aggregator framework.

* Provide some annotation for OAL.

# 1447
Use `GET /api/v1/watch/namespaces/{namespace}/pods` api to watch pod's
containerIp which help collector containers to discovery each other.

* Receiver, aggregate, server finished.

@lemon @ascrutae I change the proto file path for preparing 6.0, but didn't change .net namespace. But I think if you sync the protocol submodule, you still need some changes.

Fix #1435

* #1447

Fixed the after method interceptor for the apache http client NPE error when the response is null cause by the doExecute method throw a exception.

Make the icon font things more clear in NOTICE, include where they are in our source folder. Also move the text at the beginning of the distribution NOTICE file. (#1444)

* 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