api: update Rakefile after removing app.rb
api: add Collection model
api: add Card many to many Collection association
api: update models requires
api: generic lib: add numeric? to String
api: fix missing ActiveRecord connection in Sinatra
api: update reply_with_error function
api: add some docs
api: create basic CollectionsController structure
api: update base reply data structure
api: add app:run rake tasks
api: cleanup