Add bandit in tox -e pep8

Add bandit tox environment and amend pep8 env to run it.
Also, fix bandit errors with "0.0.0.0".

Change-Id: Ieb5785abd945663e07c07f0ddd3d9a074004f46a
Closes-Bug: #1594423

watcher/api/app.py

@@ -30,7 +30,7 @@ API_SERVICE_OPTS = [
                 default=9322,
                 help=_('The port for the watcher API server')),
     cfg.StrOpt('host',
-               default='0.0.0.0',
+               default='127.0.0.1',
                help=_('The listen IP for the watcher API server')),
     cfg.IntOpt('max_limit',
                default=1000,

watcher/api/config.py

@@ -22,7 +22,7 @@ from watcher.api import hooks
 # See https://pecan.readthedocs.org/en/latest/configuration.html#server-configuration # noqa
 server = {
     'port': '9322',
-    'host': '0.0.0.0'
+    'host': '127.0.0.1'
 }
 
 # Pecan Application Configurations