Move IP testing functions to satori/utils.py

Other modules could want access to these functions in the future
and this cleans up satori/discover.py.

Change-Id: I6954e073c16150e90525218d1d8a15525db70110
Allow running satori on localhost

Still needs style, unittests, and a no-regression promise.

Change-Id: Ia6bf6f5d1e4bcadb414eb79bb9673fbc60d1c9a6
Implements: blueprint satori-localhost