Merge pull request #18 from keithws/master

Updated tests for node-whois
Bump version
Added local file cache to store results for 24 hours.
Updated README with cache option.
Fixed typo by removing unnecessary comma.
Changed the indent for the cache setting to match the other settings.
Don't cache bad results.
Remove outdated cache files.
Added test to check if the cache respects different options.
Changed cache key to a hash of the address and options of the lookup. Prepend options to cache file for reference.