Seed directory work

Start of the directory work. Alot of this initial structure is inspired by/copied from thisandagain's badgecrawler, with the major difference being:

- API response structure ({ total: int, limit: int, data: [...badge classes...]})
- Storing in nedb (https://github.com/louischatriot/nedb). Also storing an index in lunr, but nedb is simple, embedded and since it's just a document store capable of searching on specific fields. Even though this is mvp work, I think it's important that it can intelligently search by specific pieces of data (tags, for instance)
- Using restify, instead of a low level http server