Add devise, omniauth, paper_trail gems to begin AAA.

Conflicts:
	Gemfile.lock
	config/routes.rb
Import Devise login pages. Port the Sign In page to HAML.

Conflicts:
	app/views/shared/_global_nav.html.haml
Rewrite the Devise erb as haml.
Let there be Google OAuth2

Conflicts:
	Gemfile.lock
Add OmniAuth callbacks to lookup / create accounts on the fly.
Default to auth disabled.
Fix global nav in light of auth_enabled flag.
Time for paper_trail.

Conflicts:
	Gemfile.lock
Add auth_allow_registration
Begin marking models for paper_trail.