Add caching to Localization

[Ygg01]

Motivation

To further speed-up access, we need to allow the memoization/caching of values.

What this means

Right now when you access a Bundle, the system will always run a message finding algorithm. We can do better.

For a given Locale, message-id, and variables (aka Input) we can check if the value isn't already in the Dictionary<Input, String> if it is, we return it otherwise we run the resource finding algorithm.