Contributions updates

- [ ] Use the query builder to let people build an asset table, or point to a public collection
- [ ] Freeze authors who come from data assets, dropdown for "skipping" them
- [ ] Pull authors from Github Code
- [x] Lead/++/+ for contributions
- [x] Remove sections from individual credit make them their own thing, add timeline info
- [x] Allow sections and timeline to be turned on/off by admins