Change amenity to tourism for chalet

Supersedes #226
Fixes #236

![89312](https://f.cloud.github.com/assets/1190866/1357198/fc4c8818-378b-11e3-9fe4-f0af60d8e0a4.png)![89312](https://f.cloud.github.com/assets/1190866/1357199/05112ca6-378c-11e3-9867-0bd9ed984b23.png)