Add navigation header

[joseph-behrens]

Add navigation header to the website so that users can navigate from the home page to the preferences page and vice versa.

@nplutt I'm willing to help out. This was the first on your list, but let me know if I should grab something else.

[nplutt]

Sounds good to me! I'm using the react bootstrap library, there's a component in there that you can probably use.

The document is pretty limited, this should get the UI up and running though:

cd ui
npm install
npm run start

[joseph-behrens]

I was afraid you were going to say that :)
I've tried that a couple times last night and just now but I get an error about missing ../lib/api from src/pages. I did some digging but couldn't figure out if there was a missing package or build step.

(I'm just commenting out the calls to api for now to be able to run it since I don't need to test submitting anything)