Linting task should lint this role and all dependencies

This is a common pattern in many other independent role
repositories and should be consistent across all of them.

Change-Id: I8ca656ceebf04aade2b3e9a677cf2ccd2c52f388

tox.ini

@@ -101,6 +101,13 @@ commands =
 
 [testenv:ansible-lint]
 commands =
+    rm -rf {homedir}/.ansible
+    git clone https://git.openstack.org/openstack/openstack-ansible-plugins \
+          {homedir}/.ansible/plugins
+    ansible-galaxy install \
+          --role-file={toxinidir}/tests/ansible-role-requirements.yml \
+          --ignore-errors \
+          --force
     ansible-lint {toxinidir}/tests/test.yml