Remove Bootstrap css

We'll be using Bourbon, Bitters, and Neat.
Add Bourbon, Bitters, and Neat assets.

Bourbon: A simple and lightweight mixin library for Sass.
Bitters: Scaffold styles, variables and structure for Bourbon projects.
Neat: A lightweight semantic grid framework for Sass and Bourbon.
Add jQuery lib

`bower install`.
Remove SQLAlchemy, Flask-SQLAlchemy and Flask-Migrate support

App will function as a static site generator.
Change FLATPAGES_ROOT to "articles"
Create freezer instance when required
Setup assets and templates, scaffolding