More VacTrak

- Added private field to VacID (migration included)
- Added scheduler task, prune_stale_vacids, to remove older vacids that
no one is tracking
- Fixed lots of alerts stacking up on the fronted
- Refactored search route, you now need go to the users page before
adding them
- Track whether a VacID has private profile
- Added requires helper which insures certain HTTP params are passed
- Refactor some routes