* [skip-ci] Initial Azure-Pipelines configuration.
The following configurations are tested
* macOS 10.13
* ubuntu 16.04
* Windows Server 2016
Under each operating system, the following Qt bindings are tested
* conda based pyqt4
* conda based pyside
* conda based pyside2 (5.6)
* conda based PyQt5 (5.9)
* pip basedd PyQt5 (5.12)
* pip based PySide2 (5.12)
For each configuration, it runs `python -m pytest --cov pyqtgraph -sv`
The only configuration that actually passes all tests is Ubuntu-pip-PyQt5
