update batfire, add firebase.json, security rules and firebase-simple-login
nav > jumbotron
tutorial version
cleanup
Merge branch 'tutorial'

Conflicts:
	app.coffee
	build/app.js
	build/application.js
	build/templates.js
	config/security_rules.json
	controllers/posts_controller.coffee
	html/posts/index.html
	html/posts/show.html
	index.html
	models/comment.coffee
	models/post.coffee
	vendor/batfire.js