Case conversion

[henrygarner]

My multi-word snake_case rails associations were not being picked up correctly. I'd have liked to use the 'key' property on the associations to translate, but I couldn't see how to do this (it would seem to involve looping through all defined associations for a record type and creating an association key -> property name map). Instead, I've assumed that we'll always be using snake_case on the server side and camelCase in Sproutcore. This isn't ideal, but seems to me a small improvement on no conversion at all.