Added automated testing via tox and zuul.

We're cheating a little bit and re-using the
openstack-tox-snap-with-sudo template, even though this isn't strictly
speaking a python project.

Currently, we simply build the snap and run tests/basic-test.sh.

In the long run, we will put together a more comprehensive suite of
functional tests.

Change-Id: I968116dd7bec412a55813c896d60cfc86c7070db

.gitreview

@@ -0,0 +1,4 @@
+[gerrit]
+host=review.opendev.org
+port=29418
+project=x/microstack.git

.zuul.yaml

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+- project:
+    templates:
+      - snap-jobs

test-requirements.txt

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+petname

tox.ini

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+[tox]
+envlist = snap
+skipsdist = True
+
+[testenv]
+install_command = pip install {opts} {packages}
+setenv =
+    PATH = {env:PATH}:/snap/bin
+passenv = HOME TERM
+whitelist_externals =
+    sudo
+    snapcraft
+
+[testenv:snap]
+deps = -r{toxinidir}/test-requirements.txt
+commands =
+    sudo apt update
+    sudo apt install -y snapd
+    sudo snap install core18
+    sudo snap install --beta --classic multipass
+    sudo snap install --classic snapcraft
+    snapcraft clean
+    snapcraft snap
+    {toxinidir}/tests/basic-test.sh