Add Azure Pipelines build badge

README.md

@@ -9,6 +9,7 @@
 
 [![PyPI version](https://badge.fury.io/py/jupyterlab.svg)](https://badge.fury.io/py/jupyterlab)
 [![Build Status](https://travis-ci.org/jupyterlab/jupyterlab.svg?branch=master)](https://travis-ci.org/jupyterlab/jupyterlab)
+[![Build Status](https://dev.azure.com/jupyterlab/jupyterlab/_apis/build/status/jupyterlab.jupyterlab?branchName=master)](https://dev.azure.com/jupyterlab/jupyterlab/_build/latest?definitionId=1&branchName=master)
 [![Documentation Status](https://readthedocs.org/projects/jupyterlab/badge/?version=stable)](http://jupyterlab.readthedocs.io/en/stable/)
 [![Google Group](https://img.shields.io/badge/-Google%20Group-lightgrey.svg)](https://groups.google.com/forum/#!forum/jupyter)
 [![Join the Gitter Chat](https://img.shields.io/gitter/room/nwjs/nw.js.svg)](https://gitter.im/jupyterlab/jupyterlab)