Naive attempt at keeping crc cache around between runs

I needed a good distraction for an hour or two, so I thought I'd take a swing at #25. It did knock a "cold" build of Ractive from ~15 seconds to ~4 on my machine. I feel like I shouldn't make gobble keep .cache directories around, but without a bigger refactor than I'm capable of at this point, I couldn't see a way around it.

Anyways, I figure this is at least a fair proof of concept.