fix_duplicating_css_ids_bug: generate id with prefix
refactor breadcrumb helper

+ ActiveRecord#find accepts a string (even when searching for a numeric ID)
+ removed unnecessary begin/rescue/end block; used nil-returning method alternatives
+ use `path` instead of `fullpath` to get rid of query parameters (we already leave them out)
added admin/application_controller.rb to the install generator, changed ActiveAdmin::BaseController to inherit from Admin::ApplicationController

added application_conrtoller.rb to templates

changed authorization.rb to use the proper inheritance for BaseController