0.4.0 Honoring env-vars, daherized keywords; send rubyized json keys

Squashed commit of the following:

commit 5e44bd485356132a0d6107b60a9e4a07411d37ce
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Aug 29 14:14:52 2013 +0200

    Only export env-vars as env.vars when executing a script

commit 08aa6259d0d8b972fc1bfdf834bae405eae3c2a3
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Aug 28 23:09:27 2013 +0200

    ... sending keys the ruby way and underscore env keys ... test pending

commit abd14216e5af51966e3aeab5d453b5fd97d882a6
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Aug 28 22:48:11 2013 +0200

    Dasherizing keys ...