components

Was thinking including `nanocomponent` might make sense. Perhaps a lil "hi there" screen with a main route and 404 route set up, including a lil header or smth. Then also include [assert-snapshot](https://github.com/yoshuawuyts/assert-snapshot/) with `tape` so folks can figure out how to do UI testing right.

Depends on new nanocomponent.

cc/ @bcomnes

### todo
- [ ] create header component (`components/header.js`)
- [ ] setup testing (`test/index.js`, `test/header.js`)
- [ ] create a `test-save` script (or similar) to save the new snapshot