Override for Deferred support

Hashie::Mash normally standardizes all keys as strings We can override this method to standardize as symbols either, for backwards-compat with previous Confstruct. Turns out changing this effects things like merges into ordinary hashes that client code might be doing, and makes a backward compat nightmare.

Alias for deep_copy

We need an inspect that does not evlauate Deferreds. We use fetch instead of #[], since fetch does not evaluate Deferreds. Otherwise copied from hashie‘s pretty_inspect

values override needed to ensure Deferreds get evaluated