Improve web-ui submissions

- Generate WTF form classes dynamically for all groups
- Use 'artifact' instead of 'archive'
- Rename nav bar link 'Submit archive' to 'Submit'
- Navbar submission link is now drop down to provide for all groups
- Remove complex validations, simplify forms
- Add submit_artifact.html
- Update submission routes to be /submit/<group>/
Remove unused templates
Handle empty coordinates correctly for web-ui