Sort the resource type and building facets by index.

Fixes #878 

### Before
![facet-sort-before](https://cloud.githubusercontent.com/assets/96776/4197309/82c7862a-37e7-11e4-8ad1-1b2be30edfe1.png)

### After
![facet-sort-after](https://cloud.githubusercontent.com/assets/96776/4197310/82c859d8-37e7-11e4-9897-2d80d7d590fd.png)