dynamic *translations* var

Circle relies on keywordization, but now also has a need to selectively disable keywordization for storing nested homogenous map data with sub keys that are not necessarily valid keywords. We already do some custom coercion on our side, but it would be preferable to apply that coercion globally across also congomongo operations. This PR adds a `*translations*` var which operates at the same level of `*keywordize*` to allow hooking conogomongo's various coercion functions.