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

Sounds good to me :+1: 

FWIW We can get the user's date/timezon via the Location API which we should be able to access in here, https://duck.co/duckduckhack/location_api