Enhance CI pipeline

- Support for Pull Requests
- Display build status on commit
- Notify build results on slack
- Support for releasing to artifactory

Closes gh-771

ci/tasks/stage.yml

@@ -0,0 +1,11 @@
+---
+platform: linux
+inputs:
+- name: git-repo
+outputs:
+- name: stage-git-repo
+- name: distribution-repository
+caches:
+- path: maven
+run:
+  path: git-repo/ci/scripts/stage.sh