Add checks to check for attempted duplicate additions of things in admin panel.

This code should prevent any nasty 500 errors resulting from attempts to add duplicate badges/assertions/people/issuers/authorizations via the admin panel.
Think the way to resolve this is just converting the inputted name to the id before checking as per those lines you referenced?
```
badge_id = name.lower().replace(" ", "-")
bad = ['"', "'", '(', ')', '*', '&', '?']
replacements = dict(zip(bad, [''] * len(bad)))
for a, b in replacements.items():
    badge_id = badge_id.replace(a, b)
```