[Security] Implement bandit

Bandit (https://github.com/openstack/bandit) is a python
security linter.

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

.travis.yml

@@ -8,7 +8,9 @@ install:
   - pip install -r requirements.txt
   - pip install -r requirements-test.txt
   - pip install -q coverage coveralls --use-wheel
-script: py.test --cov=puppetboard --pep8  -v
+script:
+  - py.test --cov=puppetboard --pep8  -v
+  - ./bandit.sh
 
 after_success:
   - coveralls