0.2.1 (#386)

* Fix #169

* Polish : #324 & #325

* Polish : #315

* Polish : #321

* Polish : #321

* Polish : #321 for test case

* Polish : Update Demos

* Polish : Update version to be 0.2.1

* Polish : #319

* Polish : #226

* Polish : #309

* Fix the test case's bugs

* Fix the test case's bugs

* Fix a JavaDoc issue

* Update SNAPSHOT and add exclude list

* Update SNAPSHOT to be 0.2.1-SNAPSHOT

* Update JDK versions

* Update JDK versions

* Reactor & remove author info

* Refactor : to save a shutdown hook thread

* Remove javax.servlet:javax.servlet-api:3.1.0 that may cause class conflict, and use indirectly dependencies from spring-boot-starter-*

* Polish #341

* Add the samples

* Add a license

* Add the samples of Zookeeper and Nacos

* Update README.md

* Fix the test cases

* Polish #366

* Polish #370

* Polish #370

* Add NOTICE and DISCLAIMER

DISCLAIMER

@@ -0,0 +1 @@
+Apache Dubbo is an effort undergoing incubation at The Apache Software Foundation (ASF), sponsored by the Incubator. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.

NOTICE

@@ -0,0 +1,14 @@
+Apache Dubbo (incubating)
+Copyright 2018-2019 The Apache Software Foundation
+
+This product includes software developed at
+The Apache Software Foundation (http://www.apache.org/).
+
+This product contains code form the Netty Project:
+
+The Netty Project
+=================
+Please visit the Netty web site for more information:
+  * http://netty.io/
+
+Copyright 2014 The Netty Project