border-router example for sensinode devices.

This example is meant to be used with tunslip6 in tools/

- Build the code and load it onto your node
- Connect your node to your PC over USB
- run:
  sudo ./tunslip6 <address v6>/<prefix>
  
  This will setup tun0 on your PC over device /dev/ttyUSBx. The address
  argument should contain the v6 address that you want to assign to tun0
  The node will use this address to obtain the network prefix
  
  for example:
  sudo ./tunslip6 aaaa::1/64
  This will use aaaa:: / 64 as the prefix for the 15.4 network.
