Convert badges over to using the Javascript Issuer API

This contains several significant changes:
- There is now only a single Badges page
- Clicking on a person's name pops up a dialog box showing the assertion details
- This dialog has a button which adds the badge to one's Mozilla Backpack
- bin/badge.py now only produces JSON assertions (doesn't bake badge pngs)
- Email addresses are now hashed in assertions
- Deleted badge images
- Re-added assertions with salted emails and the correct version (0.5.0).
- .htaccess URL redirection for the old individual badge kind pages