Today you can answer your front door in Miami while you are on vacation in New York and tell the stranger on your porch, in real time, that you would just love to open the door and attend to his or her needs but you are upstairs cleaning the family's weapons arsenal and can't possibly dart down the stairs at the moment. Home security - smart cameras, home automation, keyless locks that run off smart phones, smart alarms - has become really, well, smart.