Introducing a typographic scale and some house-keeping

Summary of changes:

* Replaces reference to minified Bootstrap CSS with raw CSS for during dev
* Updates $base-font-size and adds custom typographic scale variables
* Removes font-size: 21px;, adds more info about file structure, tweaks font-sizes using typographic scale
* Removes minified CSS for the time being, updates compiled raw CSS files
* Adds a .gitignore to clean things up!