KillSwitch + Device Deletion

* Killswitch plugin looks for read access to /dev/rfkill before loading Fix: #17 

* Device.py was throwing an error because we were attempting to use functions within a deleted object.
After an object is called upon by `__del__` we cannot use it anymore so, `self.foo` will not work in `self.__del__`

* SIGTERM Support for other applications in apps
TODO: Ensure Graceful disconnection from deleted Device objects.