Changes
Add **Index** health check class
This differs from the **Health** check class, which is cluster-wide.
This uses the `client.cat.indices` method to get ONLY the health status (`h='health'`) of 1 index, `format='json'`.
{'health': 'green'}
It can be `green`, `yellow`, or `red`.
This will _possibly_ work for `mount`, and other actions. TBD.