* Change some codes to make zipkin receiver works, not done yet.
* @adriancole Zipkin receiver is coming back again.
* Fix document and fix for Zipkin receiver.
* Fix some bugs.
* Fix register bug.
* Fix transfer bug for new backend core.
* Lock oracle and resin plugins version.
* Move resin and oracle plugin to openskywalking
* Restore submodule active.
* Add another submodule active command.
* Remove the wrong test cases in release and fix some doc issues.
* [maven-release-plugin] prepare release v6.0.0-alpha
* [maven-release-plugin] prepare for next development iteration
* Fix some doc
吴晟 Wu Sheng
彭勇升 pengys