added purecss.io stylesheet & form styles
vue.js doing one time interpolation

Based on
https://github.com/yyx990803/vue/commit/8cd19f0fdb08f4523c9d6773da0e8a390efadbd3
switching to `doc` object for output JSON
component-ize the main editor
removed excessive `v-with`
getting closer to working sub-schemas

Still no fields being output, but we do have
headers (fieldsets) now.