Selecting staff

[jfly]

This exists in two places: /manage/<comp_url_id>/staff and the checkin page on /manage/<comp_url_id>/check-in.

• Include the WCA ID in the names so we can actually verify people's identities.
• For staff, prioritize delegates? A visual indication would be nice (such as the WCA logo or some variant). This should definitely be a separate issue, however.
• I'm getting a bunch of Warning: Unknown props errors.
• The add button isn't actually doing anything for me, I just see 72 "adding" [Object] in my console.