Use stestr as the test runner for unit tests

This patchset changes Armada to use stestr instead of pytest
for running unit tests as it is the officially sanctioned
test runner in OpenStack [0].

[0] https://openstack.nimeyo.com/119685/openstack-dev-recent-changes-in-testr-and-migrating-stestr

Change-Id: I4f1320968990d9d9cc4d50cac0f2eecc3a0d331c

test-requirements.txt

@@ -12,6 +12,4 @@ testtools>=2.3.0 # MIT
 os-testr>=1.0.0 # Apache-2.0
 flake8>=3.3.0
 mock
-pytest==3.2.1
-pytest-mock
 responses>=0.8.1

tools/run-unit-tests.sh

@@ -1,15 +0,0 @@
-#!/usr/bin/env bash
-
-# Script for passing regex filtering of unit tests to py.test conditionally.
-# Needed because tox currently doesn't support conditional logic like this.
-
-posargs=$@
-if [ ${#posargs} -ge 1 ]; then
-    py.test -vvv -s --ignore=hapi -k $1
-else
-    py.test -vvv -s --ignore=hapi
-fi
-TEST_STATUS=$?
-set -e
-
-exit $TEST_STATUS

tox.ini

@@ -18,8 +18,13 @@ whitelist_externals =
     rm
 commands =
     find . -type f -name "*.pyc" -delete
-    python -V
-    {toxinidir}/tools/run-unit-tests.sh {posargs}
+    rm -Rf .testrepository/times.dbm
+
+[testenv:py35]
+commands =
+    {[testenv]commands}
+    stestr run {posargs}
+    stestr slowest
 
 [testenv:docs]
 deps = -r{toxinidir}/doc/requirements.txt