Add multiple claimants to the flow (WIP)

- [x] Add multiple claimants to the flow
- [x] Hypenate URLs #296 
- [x] Non-JS solution to non-destructively add claimants
- [x] i18n
- [ ] Styling
- [ ] Progressive reveal
- [x] Destruction of arbitrary claimants
Did this subclass so we don't have to have this code path for every form submission, only the routes set up with this controller.