Add bandit to pep8 venv

Bandit is considered a linter much like pep8. So by request from
the infra team, the bandit job is being made part of pep8 venv.
The bandit testenv needs to stay however for the bandit integration
job.

Change-Id: I83d27217a9ffe8a882342442072272a250eb818c

tox.ini

@@ -29,6 +29,7 @@ commands =
 commands =
     flake8 {posargs} anchor
     flake8 {posargs} tests
+    bandit -r anchor
 
 [testenv:venv]
 commands = {posargs}