[WIP] Badge categories (resolves #330)

**Requires [streamsql #16](/brianloveswords/streamsql/pull/16) be merged before this will work.**

This is functionally complete, and can technically be merged as is (with the above caveat) - users can add categories to badges - but is missing any front-end flourish.

To do:
 - [ ] Update `package.json` appropriately, as and when the [streamsql pull request](/brianloveswords/streamsql/pull/16) is merged *(required)*
 - [ ] Allow users to add/remove input rows - currently, (at least) three inputs are provided
 - [ ] Add admin option to edit category list