Remove all bytcode & objectcode before running tox

Currently __pycache__ directory, which also holds
python bytecode is not deleted when running tox.
TrivialFix

Change-Id: I0fdcf9a3f9b01cee813eefdbfe29d208dd67f826

tox.ini

@@ -14,7 +14,8 @@ passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
           OS_STDOUT_CAPTURE OS_STDERR_CAPTURE OS_LOG_CAPTURE OS_TEST_TIMEOUT
           PYTHON OS_TEST_PATH LISTOPT IDOPTION
 commands =
-  find . -type f -name "*.pyc" -delete
+  find . -type f -name "*.py[c|o]" -delete
+  find . -type d -name "__pycache__" -delete
   python setup.py test --slowest --testr-args='{posargs}'
 
 [testenv:pep8]