Cache Hamm

re-opening for visibility and to hear more opinions on this feature; I can see it being valuable for certain situations.

json-path requires a decent amount of overhead; it's a relatively complex spec. I'm not surprised that using the `path` feature on a large number of items is causing significant impact....

@justinfagnani would you mind publishing a new version please? It's really confusing to browse the repo and see tests around behavior that doesn't exist in what's published on npm.