add start of header, still needs logo and collapsing logic

Adding the start of the header. Found this image on Unsplash and it kinda of fit nicely I thought and has a good color scheme, and had a nice tie with the duo of people in the image, but open to different ideas.

Here's the down:

![](https://i.cloudup.com/fAeC727JoM.png)

And then up you'd just see the very top of it (and there would be a search form and a smaller logo):

![](https://i.cloudup.com/njKloP4tYH.png)

Still need to get the logo file created in that other repo, going to use the `logo/logo` pattern if that's cool to make it modular and require it in. I think we'll need a description and maybe even the name towards the bottom of the image, because the graphic logo by itself doesn't given people enough information on first sight.

- [x] Add white logo in middle.
- [x] Add "Duo" and tagline at bottom.
- [ ] Add search box.
- [x] Add "View on GitHub" banner in top-right.
- [ ] Add Javascript logic to properly transition between regular and collapsed states.