Fix bandit error: [B104:hardcoded_bind_all_interfaces]

This patch fixes one of the cyborg-tox-bandit Failures[0] in Zuul check,
the rest will be in the following patches.

[0]https://c3f93530c9211d80493c-aff6bc2b39e4d26360d25c473974606e.ssl.cf5.rackcdn.com/696089/16/check/cyborg-tox-bandit/e8316b7/job-output.txt

Change-Id: I8ef483d4d2082f117aae75c53321bf194791610f

cyborg/api/config.py

@@ -17,7 +17,7 @@
 # See https://pecan.readthedocs.org/en/latest/configuration.html#server-configuration # noqa
 server = {
     'port': '6666',
-    'host': '0.0.0.0'
+    'host': '127.0.0.1'
 }
 
 # Pecan Application Configurations

cyborg/conf/api.py

@@ -20,7 +20,7 @@ from cyborg.common.i18n import _
 
 opts = [
     cfg.HostAddressOpt('host_ip',
-                       default='0.0.0.0',
+                       default='127.0.0.1',
                        help=_('The IP address on which cyborg-api listens.')),
     cfg.PortOpt('port',
                 default=6666,