Add browse page

A few components here:

- the actual browse page
- a new model to contain a summary for each address, which is viewed on the browse page
- a script to populate the db with the above summaries (probably run once/day by cron job in production)
- tests!
Err, I'm not sure we're doing the same thing for fire/police. This is aggregating all of the licenses into a big list per address, while fire/police are tracking counts per address. Unless you're referring to somewhere else?