fixes #2411 - add autoload_paths in application.rb in preparation for file location changes
fixes #2411 - move files in /models to /concerns, /services, /mailers, /observers
fixes #2411 - move STI models in /models and /lib/foreman/models to sub-folders
fixes #2411 - move to controller/concerns
fixes #2411 - move files to /app/services
fixes #2411 - move lib/audit_extensions lib/fog_extensions lib/foreman to models/concerns
fixes #2739 - add ActiveSupport::Concern syntax to mixins
fixes #2740 - copy code from lib/foreman.rb to initializers/foreman.rb
fixes #2741 - Minitest refactoring
fixes #2741 - remove unnecessary require statements