pass in query params to res.locals for download button
add <aside> link for downloading zip file
remove grid-router, add requires
remove grid-router subclass
beef up grid-model with stringify() method, attribute validations
Change architecture so that views directly manipulate model.

Instead of classical MVC, the views directly update the model.
The router in start.js listens for model change events and updates
the route, which triggers a view.render()
remove duplicated handlebars-runtime dependency
add HTML5 form validation
minor tweaks to CSS and DOM