[WIP] Make badge, issuer, program undoably deletable.

Fixes #237.

Things to do:
- [ ] Make badge/issuer/program models undoably deletable.
- [ ] Make undoable deletion of program cascade to badges.
- [ ] Make undoable deletion of issuer cascade to programs, badges.
- [ ] Add UI/routes for deleting badges/issuers/programs. UI should have confirmation dialog.
- [ ] Add UI/routes for undeleting badges/issuers/programs.