Enable bandit runs for tox

This patch adds tox settings for running tox -ebandit
to look at potential security issues.

Current issues:
  scaleio connector disables SSL cert verification.

Change-Id: I79bec423a051eb12ab53042840a519bd4a77b4da

test-requirements.txt

@@ -15,3 +15,4 @@ castellan>=3.7.0 # Apache-2.0
 pycodestyle==2.6.0 # MIT
 doc8>=0.8.1 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
+bandit>=1.6.0,<1.7.0 # Apache-2.0

tox.ini

@@ -50,6 +50,10 @@ envdir = {toxworkdir}/pep8
 commands =
     {toxinidir}/tools/fast8.sh
 
+[testenv:bandit]
+deps = -r{toxinidir}/test-requirements.txt
+commands: bandit -r os_brick -x os_brick/tests -n5
+
 [testenv:pylint]
 deps =
        -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}