Rework the Stylesheet

I added two new sections. Helpers are where classes used with @extend
are placed. Classes is a place for classes not part of the page structure.

I also changed the styles for the homepage to only work on it, so its
styles don't bleed over into the new About page.

And finally I changed the classes in the homepage so the styles are applied.
Add new partials and edit stylesheet
Style Headers, Paragraphs, and move `html {}` contents to `body {}`