Add support for Name Answering Protocol in XBDM interface

[JayFoxRox]

See this article for more information.

We should implement this independently of the rest of xboxpy.

We'll probably want a better URL scheme or other interface to xboxpy for the following, so that will be a seperate issue:
If a user wants to connect to an Xbox target, we could re-use that NAP implementation.
Discovery could be used to see if only one Xbox responds, so we can just use it as target.
If a name is supplied we could also use that name (although this might conflict with DNS).