Can update ES index settings/mappings in place

Potentially breaking change, depending how your migrators are written and how they are deployed.

update-index now updates the index mappings and settings in place. There are many caveats to what you can change in place in ES. For things that you can't change, clone-index has been changed to behave like the old update-index did - that is, it creates a new index, copies over all settings and mappings (with optional deltas that you can supply) and points the alias at the newly created index.