working version

Hello!

I had trouble figuring out how to get your provided build pack to work. 

This now works at least for our specific use case where we only needed the country db. A good improvement would be some sort of env switch to specify whether you want the country db or the cities db, but I don't have time at the moment -- so if you'd like the other behavior change the comments. 

Do you have any idea how to detect if the libraries are already installed so we wouldn't need to rebuild each time?

Nathan