add bandit to pep8 job

Add the bandit security scanner to the pep8 job.
Note: we skip some cases which we can't fix now.

Change-Id: Iad8b31d1c214376cbdca39fa28afa7f46af6ccca

test-requirements.txt

@@ -14,3 +14,6 @@ sphinx>=1.6.2 # BSD
 reno>=2.5.0 # Apache-2.0
 
 eventlet!=0.18.3,!=0.20.1,<0.21.0,>=0.18.2 # MIT
+
+# Bandit security code scanner
+bandit>=1.1.0 # Apache-2.0

tox.ini

@@ -14,7 +14,12 @@ commands =
     env TEST_EVENTLET=1 lockutils-wrapper python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:pep8]
-commands = flake8
+deps =
+  -r{toxinidir}/test-requirements.txt
+commands =
+  flake8
+  # Run security linter
+  bandit -r oslo_concurrency -x tests -n5 --skip B311,B404,B603,B606
 
 [testenv:venv]
 commands = {posargs}