Change to nose2

Use nose2 instead of stestr for running unit test as nose2 provides
junit-style xml output that can be reported in Jenkins to show test
pass/fail and trend history.

Change-Id: I3f57992ca7252bfd5403f7fdf7153d1faa232e71
Signed-off-by: beierl <mbeierl@vmware.com>
diff --git a/tox.ini b/tox.ini
index 03f2d27..b5c0df0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,7 +25,7 @@
 # test suite on all supported python versions. To use it, "pip install tox"
 # and then run "tox" from this directory.
 [tox]
-envlist = py3, flake8, pylint, cover
+envlist = cover, py3, flake8, pylint
 
 
 [testenv]
@@ -41,12 +41,12 @@
 
 [testenv:cover]
 basepython = python3
-setenv = VIRTUAL_ENV={envdir}
-         PYTHON=coverage run --source osm_mon --omit='*tests*' --parallel-mode
+deps = nose2
+       -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
 commands =
   coverage erase
-  stestr run {posargs}
-  coverage combine
+  nose2 -C --coverage osm_mon --plugin nose2.plugins.junitxml
   coverage report --omit='*tests*'
   coverage html -d ./cover --omit='*tests*'
   coverage xml -o ./cover/coverage.xml --omit='*tests*'