Restrict post-login redirection targets to local URLs
fixes #1809
restrict intro page to copyright tags
add dedicated intro post set
Merge pull request #1813 from kxz/login-redirection

Restrict post-login redirection targets to local URLs
Merge branch 'master' of github.com:r888888888/danbooru
Merge branch 'master' into omnibooru

Conflicts:
	app/controllers/sessions_controller.rb
Fix ActiveModel::MissingAttributeError in user promotions report

Give the view a page title too, while we're at it.