San Francisco-based Boombotix has posted a Kickstarter page to raise funding for a new accessory for the sixth-generation iPod nano. Dubbed “The Proof,” the accessory is a watch kit for the device, made from polyurethane, coated with a thick silicone wrapping. It aims to provide IP68 waterproof coverage down to three meters by plugging all ports and allowing access to the nano’s screen via an ultra thin polycarbonate lens, and using…