define range of tier sidecar versions that are supported

- If not a version that has the required support for a given feature, throw an error when using that feature.
- If a _newer_ version than known supported, print "I'll do my best" warning.

Probably good to do this in a way that avoids having to pull in all of node-semver, but that's of course an option to keep in mind if the logic gets too convoluted.