Adds a multi claimants CSV validator

- [x] Add csv processing
- [x] Add the form component
- [x] Add the view
- [x] Tidy up tests
- [x] Fix sync with file removal
- [x] Fix transition manager page numbers
- [x] Fix reveal JS
- [x] Link group claims to upload page & vice versa + spreadsheet download link
- [x] Styled correctly(@cleargif)
- [ ] File upload size(@MatthewM)