Set all devices to None before shutdown

Ignore-this: 1d47f839f43a1a0f1d1be801dc8f1f9c

darcs-hash:20100812085134-56b4d-bd5eccac8134d21b310f0a5b11e641f13fbb75bf
Made the reactor thread a daemon thread

Ignore-this: f95558056749b3273ed301b9f3cdd4

darcs-hash:20100813075044-56b4d-317f60f15c4f4ebb6e2bdeaef748036205586248