firewall_gui: fix missing json import

firewall_gui/views.py

@@ -5,6 +5,8 @@ from django.contrib.auth.models import User
 
 
 from firewall.fw import *
 from firewall.fw import *
 from firewall.models import *
 from firewall.models import *
+import json
+
 
 
 def req_staff(user):
 def req_staff(user):
     ''' decorator function for user permission checking '''
     ''' decorator function for user permission checking '''