Rework policy divisions nav

Changes the policy divisions navigation to a link back and forth style, rather than nav tabs. Includes a slight edit on the policy's divisions intro copy.

![screen shot 2014-10-09 at 5 01 18 pm](https://cloud.githubusercontent.com/assets/1239550/4571581/e76dfb32-4f79-11e4-87f2-054024d53c03.png)
![screen shot 2014-10-09 at 5 01 28 pm](https://cloud.githubusercontent.com/assets/1239550/4571582/e790b4b0-4f79-11e4-9f34-38c5ccceeb96.png)

fixes #673