use private IPs with nodepool
use private IPs with nodepool

our cloud doesn't inherently have public ips, and the default
behavior of using a floating IP for each instance is .. problematic

Just use private IPs since nodepool and managed slaves are on same
cloud.

Change-Id: I565c1425b7bef026e7705fe5dcf4c9421ac8fd4f

Tesora/tesora-nodepool,Tesora/tesora-nodepool