Support for standalone form export

[blcham]

SForms is an almost completely offline interactive form. The only thing that makes it not work offline are "PossibleValuesQueries". We should provide a function on how to export form with "PossibleValues" next to "PossibleValuesQueries".

A/C:

• there is a function in a library that can provide JSON of the form with possible-values loaded
• exported form works without the need for a server (that returns possible-values)
• [OPTIONAL] There is a way how to get the export in chrome development tool and this guide is described in some subpage referenced by main README.md

[blcham]

Related props: "http://onto.fel.cvut.cz/ontologies/form/has-possible-values-query"