Switch tox unit test command to use ostestr

This commit switches the tox command to use ostestr instead of calling
testr through setup.py. The primary advantage here is that it uses the
subunit-trace output filter. ostestr primarily exists as a replacement
for pretty_tox.sh bash scripts which spread like a plague through
OpenStack projects after Nova copied it from Tempest. (although ostestr
also provides some other useful features) Granted ironic wasn't using
that, but this commit makes the switch to enable getting the
subunit-trace output which is generally useful.

Note that this dramatically increases output while running tests.
However, test failures are still at the bottom of the output, so it
shouldn't cause much pain, if any.

Also remove requirements.txt from tox.ini deps

This is redundant, per lifeless email:
http://lists.openstack.org/pipermail/openstack-dev/2015-July/069663.html

Change-Id: Ia9e3000ddfe02979c26807ae5d130bfd2730c5e1

test-requirements.txt

@@ -5,10 +5,10 @@ hacking<0.11,>=0.10.0
 coverage>=3.6 # Apache-2.0
 discover # BSD
 mock>=1.2 # BSD
-testrepository>=0.0.18 # Apache-2.0/BSD
 testtools>=1.4.0 # MIT
 python-subunit>=0.0.18 # Apache-2.0/BSD
 oslotest>=1.10.0 # Apache-2.0
+os-testr>=0.4.1 # Apache-2.0
 
 # Doc requirements
 doc8 # Apache-2.0

tox.ini

@@ -9,11 +9,8 @@ install_command = pip install --allow-external -U {opts} {packages}
 setenv =
   VIRTUAL_ENV={envdir}
   OS_TEST_PATH=./ironic_python_agent/tests/unit
-deps =
-  -r{toxinidir}/requirements.txt
-  -r{toxinidir}/test-requirements.txt
-commands =
-  python setup.py testr --slowest --testr-args='{posargs:}'
+deps = -r{toxinidir}/test-requirements.txt
+commands = ostestr {posargs}
 
 [testenv:func]
 usedevelop = True
@@ -24,8 +21,7 @@ setenv =
   OS_TEST_PATH=./ironic_python_agent/tests/functional
   TEST_PORT=9999
   IPA_WAIT_TRIES=100
-commands =
-  python setup.py testr --slowest --testr-args='{posargs:}'
+commands = ostestr {posargs}
 
 [testenv:pep8]
 commands =