Generate Rails ERB for Legal Docs via Aglio

Instead of having Aglio generate a standalone HTML file,
have it generate a ERB partial for rails to render in a view,
which gives us headers, footers, and MyUSA styles.

This commit adds:

- myusa.jade -- a Jade template for aglio that generates the ERB
- bootstrap*.jade -- bootstrap helpers for aglio
- a route in home#legal to get to the legal page
- updated rake task
- _aglio.css.scss -- SASS implementation of aglio specific classes
Remove local file warnings from aglio

We'll always be viewing this through the rails server,
so the local file warning isn't necessary.
Merge branch 'devel' into feature/aglio-rails-legal

Conflicts resolved between contact-us and legal route:
	app/controllers/home_controller.rb
	config/routes.rb
Merge pull request #259 from 18F/feature/aglio-rails-legal

Generate Rails ERB for Legal Docs via Aglio