Closes #104

LGTM given by: @esposito

Squashed commit of the following:

commit 29f35da80d361c2d9973833ac119be5ea753d8d2
Author: Jorn van de Beek <jornvandebeek@gmail.com>
Date:   Tue Nov 4 16:11:35 2014 +0100

    Complete proper checking of whether depended on questions and options are filled in

commit 1d0a6a8e19307283f899bfea7d485854b27e64b4
Author: Jorn van de Beek <jornvandebeek@gmail.com>
Date:   Tue Nov 4 13:42:18 2014 +0100

    Failing spec for function that checks if a depends on key is answered