AMS: Failing test for decamelize with numbers

A model with keys including numbers like `size160Url` doesn't play well with the AMS adapter. Currently this key is deserialized from `size_160_url` to `size_160_url` and `size160Url` is undefined.

I'm not really sure how to fix this, as either `size_160_url` or `size160_url` can be a proper decamelized representation. @bradleypriest any idea?