Added validator using node.js and schema.validate

It does not currently validate, but possibly no point if still moving target? Perhaps deal with [issue 13](https://github.com/garyhodgson/thing-tracker-network/issues/13) first?

FTR the thing it didnt validate with; installed with `npm install schema`, (`npm show` reveals)it comes from [akidee github user](https://github.com/akidee/schema.js), not molnarg, presume that isnt the issue though.