Replace deprecated `Railties.engine`
Fix logout links

Fixes #182
Remove loose require for coffee_script

Fixes #176
updated the UserRegistrationsController#create action to respect Devise after_sign_up_path_for

Fixes #183
Fixes #181

Conflicts:
	spree_auth_devise.gemspec
Use font-awesome icons in admin/_login_nav
Typo fix in README.md