[TST] Automatic wheelhouse build using Azure Pipelines (#130)

* Set up CI with Azure Pipelines

* Try to switch to Py35

* Install requirements

* Skip Py27

* Skip Python 3.8

* Add CIBW_BEFORE_BUILD

* Add CIBW_BEFORE_BUILD_LINUX

* Update requirements.txt

* Update CIBW_BEFORE_BUILD_LINUX

* Update CIBW_BEFORE_BUILD_LINUX

* Update azure-pipelines.yml

* add new release instructions to doc

* add azure triggers

* Remove pr from azure-pipelines.yml

* Add pr to azure-pipelines.yml