Rating Middleware for CCNQ4

This useful-wind/thinkable-ducks middleware uses the rating engine from entertaining-crib and relies on data injected by huge-play's cdr middleware.

Client-side CDR is generated if the endpoint data is available in the session (this is normally done by huge-play). Carrier-side CDR is generated if the winner carrier data is available in the session (this is normally done by tough-rate).