VMware: spawn refactor - phase 1 - get_vif_info

get_vif_info converts OpenStacks nova network_info
into a data structure that is used to prepare the
configuration spec for the instance that is being deployed.

partial blueprint vmware-spawn-refactor

Change-Id: I5d1535e84de44a995e1605d0d5b850c9756612de
Merge "VMware: spawn refactor - phase 1 - get_vif_info"