Add JSON schema for JSON graph format
Add JSON schema for JSON graph format

* http://tools.ietf.org/html/draft-zyp-json-schema-04
* http://tools.ietf.org/html/draft-fge-json-schema-validation-00

Tested against draggabilly.json from the dataflow-noflo demo.

jonnor/noflo,saurabhsood91/noflo,trustmaster/noflo,saurabhsood91/noflo,trustmaster/noflo,lxfschr/noflo,jonnor/noflo,noflo/noflo,lxfschr/noflo