Option validation

[wfarr]

So I had a bit of a thought earlier. elasticsearch has a billion and one options for API requests, and it can be easy to typo one and shoot one's self in the foot without noticing as elasticsearch won't really complain.

It would involve a bit of maintenance overhead keeping up with elasticsearch releases, but for the most part the API is pretty stable.

We could well validate options on every endpoint and make super fucking useful error messages like: "indxees is not a valid option this endpoint. Must be one of [ :indexes ]" or whatever

Thoughts?

/cc @TwP @jbarnette