It was getting large and unwieldy (to the point where kubecfg was slow).
In this change, we:
- move the Cluster function to cluster.libsonnet
- move the Cluster instantiation into k0.libsonnet
- shuffle some fields around to make sure things are well split between
k0-specific and general cluster configs.
- add 'view' files that build on 'cluster.libsonnet' to allow rendering
either the entire k0 state, or some subsets (for speed)
- update the documentation, drive-by some small fixes and reindantation
Change-Id: I4b8d920b600df79100295267efe21b8c82699d5b
