refine tables, create index/new/create for users
add #show route/action/view for users
add #edit/update route/action/view to users
add #destroy route/action/view to users
add flash messages to park create/update actions
add homepage route/controller/view and edit title content for views
add check-in feature to user show view
add column on park show page to show check-ins
add input callbacks to user and park models