Added validator
Merge pull request #24 from derrickoswald/master

Make ThingMaker into a submodule.
Merge pull request #23 from o-jasper/master

Added validator using node.js and schema.validate
updated jsrsasign
updated keys to be in camelCase, rather than having hyphens
Renamed uuid to id and removed restriction on format.
Made url attribute optional.
added missing title attribute to the relationship array.
added downloadUrl; corrected some urls in the example tracker.
correction to datetime iso format regular expression - UTC (Z) indicator is optional.