Extending Dates Role's Vague String handling & Fixing #346

I've extended the handling in order to support the functionality required to fix https://github.com/duckduckgo/zeroclickinfo-goodies/issues/346

>The biggest problem may be people doing descriptive date strings around the end-of-year/end-of-month. I think it's ok, but I again defer.

I agree I don't really think this is a problem at all; as long as it's within a few hours of the client then the date'll be as the user expects.