Goodness gracious...

Some progress toward a responsive, mobile friendly navigation menu. A summary of
changes:

* Removes the courtesy, just to help me keep my sanity. Not sure we'll be
  keeping this stuff anyways.
* Adds a separate _navigation.scss file, again just to help me keep my sanity.
  (There really should be a better way to organize all this.)
* Bumps up break points because of length of menu.
* Increases font size of menu for better legibility.