If you're *nix user, you can quite easily perform this kind of stuff using date, or at least using date from coreutils.

    $ date -d 'today + 6 weeks'
    Mon Aug 24 13:15:54 CEST 2015
    
    $ TZ=America/New_York date -d 'now + 2 hours'
    Mon Jul 13 09:16:17 EDT 2015

My NLP is not top notch :D. I figured that getting the parsing intuitive would be doable given the relatively narrow field, but I was proven wrong :) The result is that you need to learn the syntax a bit before it feels intuitive.

Regarding your specific examples: You need "in _zone_ new york" ATM. I think 'weeks' is missing simply as the result of an oversight :/ Thanks for the QA.