Navbar fixes for #60

This pull request does quite a bit. It first pulls the navbar out into a re-usable view that can handle the different views.

It also enables all the action controls in the navbar so that they should work. In order to have the navbar view work independently, I've moved around the initial elements of the `index.html` page. Now the navbar goes into a `<nav>` and the content goes into a `<content>` instead of `#outer`.

The expected result of this PR is that the navbar should work, and all of the existing functionality of the app should remain unchanged. The navbar now uses `flexbox` so that the elements should always be in their respective places.

Just a few more detailed notes on changes or things to change in the future.
1. I removed _.debounce for the search because it wasn't working for some reason. That should be addressed so that we're not making a bunch of search requests
2. The navbar itself makes lots of API calls because there isn't a true model layer, and everything is backed directly by the API. We should also change that (might use React or something similar, which would also address something like #84)
3. We should use a real `ViewSwitcher` class so that the transitions aren't so choppy/abrupt.