[feature] Add possibility to restrict access to admin to specified ip ranges
Created by: hscadore
Sometimes admins don't need or prefer not to have access to the management console of a controller from an untrusted network, although they will still want clients to connect to the controller and get configurations from these same untrusted netwoks. I suggest a role variable which would enable admins to restrict access to the management console allowing only computers from trusted networks to do so while Openwrt/LEDE clients from trusted and untrusted networks will still be able to work with Openwisp. This would improve security reducing the surface of attacks such as weak passwords and possibly other types of attacks.