Run ansible-lint under pep8 envlist

Start linting our ansible playbooks, this is helpful to find basic
syntax / formatting errors.

Change-Id: I147a303841ac70ee59177c56d24758e73c04205b
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

test-requirements.txt

@@ -4,6 +4,7 @@
 
 hacking>=0.12.0,<0.13 # Apache-2.0
 
+ansible-lint
 bashate>=0.2
 sphinx>=1.5.1,<1.6.0 # BSD
 oslosphinx>=4.7.0 # Apache-2.0

tox.ini

@@ -21,7 +21,11 @@ commands = bindep test
 commands = python setup.py build_sphinx
 
 [testenv:pep8]
-commands = flake8 {posargs}
+whitelist_externals = bash
+commands =
+  flake8 {posargs}
+  bash -c "cd playbooks; find . -type f -regex '.*.y[a]?ml' -print0 | xargs -t -n1 -0 \
+    ansible-lint"
 
 [testenv:venv]
 commands = {posargs}