Add status to propositions and sweeten admin/propositions#index
admin/propositions#index: Add search UI (no backend yet)
UI for admin/propositions#edit
Add Proposition#{simple_description,simple_body}
Add up/down sort indicator
Use search index for admin/propositions#index
Use modal to show long proposition bodies.
Implement admin/propositions#update
Add Proposition#source_slugs (temporarily) + various improvements
Add progress bar admin/propositions#edit
Cleanup