Cache now stores the response body (not parsed output), and the key is simplified to just the request URL.
Cache now checks for expiry on retrieval instead of using background timers.
Changed default Redis hash name to a less generic one.
cache.resource() optionally accepts a generator function for requestOptions.
Bumped package version to 0.0.2.

* doesn't use background timers anymore
* caches responses unparsed
* allows a generator function for requests that differ on each refresh (API tokens)