Use ostestr to run unit test

The ostestr command provides a wrapper around the testr command.
By default it also has output that is much more useful for OpenStack’s
test including lists of all and failed tests and lists of the 10
slowest tests.
ref:
http://docs.openstack.org/developer/os-testr/ostestr.html

Change-Id: If005d1987b2a4e586cf35f0cc1d07739f84235d2

test-requirements.txt

@@ -17,6 +17,7 @@ psycopg2>=2.5 # LGPL/ZPL
 python-subunit>=0.0.18 # Apache-2.0/BSD
 requests-mock>=0.7.0 # Apache-2.0
 sphinx!=1.2.0,!=1.3b1,<1.3,>=1.1.2 # BSD
+os-testr>=0.4.1 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testresources>=0.2.4 # Apache-2.0/BSD
 testtools>=1.4.0 # MIT

tox.ini

@@ -12,7 +12,7 @@ deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands =
   find . -type f -name "*.pyc" -delete
-  python setup.py testr --testr-args='{posargs}'
+  ostestr {posargs}
 
 [testenv:releasenotes]
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees \