added model Deck
added settings for Decks to model Card, User
added decks_controller.rb, routes, settings to user.rb
replaced code to cards_controller.rb for support Deck
added settings for Deck to index & users controller, view
added routes for Deck
added views for Deck; fixed bugs controller cards, decks; fixed bugs layouts/application.html.erb
added views deck = edit, new; edited index/index.html.erb