Default to using ISTIO_QUIT_API=http://127.0.0.1:15020

[haf-afa]

Since I put scuttle in front of my program it would make sense that it does its job assuming an up-to-date version of istio.

[linjmeyer]

I have no issues with this being the default, but a new env variable should be added to enable/disable Scuttle with the default to false. This is necessary so that non-kubernetes environments can have Scuttle in the docker image without breaking. For example, using docker run should still work with scuttle on a developers local machine.

Feel free to do a PR, otherwise I can pick it up next week. Thanks for the suggestion!

[ptzianos]

What if we use a variable like ISTIO_VERSION to show scuttle what it has to deal with? Then we could set automatically sensible defaults like in the case of ISTIO_QUIT_API and ENVOY_ADMIN_API (#12). It's also easy to spot if it is not configured properly.