remove paper_trail
move paginators, runners, notifiers and listeners to app directory. remove service directory.
version belongs_to user with index
version in resource runner
add user_id index
versionable unique index
select necessary attributes only.
white list constantize
remove classify
white_list reviewable type
white_list resource types
refactor owner widgets
extract display and paginate method to pagination widget
white list owner types
extract safe constantize find