Prep work for a scalable control plane.

This is complete as far as it goes but it isn't enough to make running
a scaled out control plane actually work. Specifically, the constructs
to point at API hosts based on looking up a network address aren't
suirtable for scaled out - we need to be using the virtual IP or DNS
round robin or other such resilient configurations, but that is
largely / entirely orthogonal to making the template be ready for
scaling.

Change-Id: Ib9e6db5e7d5db84e4746afdabea046d2b8702bbb