Update to use os-testr to get better report

Change-Id: Iee2e7683672a1551d8a6409fab8b2166c50722b7

tox.ini

@@ -6,10 +6,13 @@ skipsdist = True
 [testenv]
 usedevelop = True
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
-setenv =
-   VIRTUAL_ENV={envdir}
+setenv = VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/test-requirements.txt
-commands = python setup.py test --slowest --testr-args='{posargs}'
+commands =
+  find gluon -type f -name "*.pyc" -delete
+  ostestr '{posargs}'
+whitelist_externals =
+  find
 
 [testenv:pep8]
 commands = flake8