Refactor navbars to simplify things

Refactor navbars to simplify things

* `.navbar-brand` is no longer centered, thus removing need for
max-width and a few lines of code
* Clear floats of `.navbar-brand` in the `.nav-collapse` like we did in
2.x, thus simplifying some clearing and other things.
* Restyle the `.navbar-toggle` button to align it's bars up with the
text and flow of the document.
* Restyle the `.navbar-brand` to not use padding on left/right as to
avoid negative margin and other fuckery. This limits the ability to put
a bg color on the brand, but I think that's fine for now.