Update azure-pipelines.yml for Azure Pipelines (#331)

* Update azure-pipelines.yml for Azure Pipelines

* Add Python build scripts.

* Run scripts with Python 3.

* Add strategy for both variants.

* Fix variables for jobs and use the right variant to build.

* Fix build and test script.

test.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+
+import sys
+from pathlib import Path
+from build import VARIANTS
+
+DOCKER_TEST="""version: '2'
+
+services:
+    mailman-core:
+        image: core-{variant}
+
+    mailman-web:
+        image: web-{variant}
+        environment:
+          - SECRET_KEY=abcdefghijklmnopqrstuv
+"""
+
+
+def test_setup(variant):
+    Path('docker-test.yaml').write_text(
+        DOCKER_TEST.format(variant=variant))
+
+
+def usage():
+    print('usage: python test.py (stable|rolling)')
+
+
+if __name__ == '__main__':
+    if len(sys.argv) < 2:
+        usage()
+        sys.exit(1)
+
+    variant = sys.argv[1]
+    if variant not in VARIANTS:
+        usage()
+        sys.exit(1)
+
+    test_setup(variant)