Add host and port variables to api server

This commit adds 'host' and 'port' configuration variables to the o-h
api server. Sometimes, default port(5000) conflicts existing port
number. And default host address(127.0.0.1) is not good remote
development environment. I think there are some workaround for this such
as portforwarding but this would be a straight forward solution.

Change-Id: I8531860757fb9c7625f7a009175af1b40ca52dc9
Closes-Bug: #1554955

etc/openstack-health-api.conf

@@ -9,3 +9,5 @@ ignored_run_metadata_keys =
   build_short_uuid
   build_uuid
   build_zuul_url
+host = 127.0.0.1
+port = 5000

openstack_health/api.py

@@ -394,7 +394,15 @@ def main():
     args = parse_command_line_args()
     config = ConfigParser.ConfigParser()
     config.read(args.config_file)
-    app.run(debug=True)
+    try:
+        host = config.get('default', 'host')
+    except ConfigParser.NoOptionError:
+        host = '127.0.0.1'
+    try:
+        port = config.getint('default', 'port')
+    except ConfigParser.NoOptionError:
+        port = 5000
+    app.run(debug=True, host=host, port=port)
 
 
 if __name__ == '__main__':