Support for /_cluster/state APIs

Initial support for monitoring of elastic via /_cluster/state.  I need to add some additional object maps around metadata and blocks, but those are not present at all in our environment.  

All the main bits are here and allow us to monitor detailed cluster state across our network - submitting this so others can do the same.

Also contained in here are fixes for NodeState, adding load averages and proper property lengths (int => long) where needed.