Add formbehavior chosen to contact selects

This PR adds formbehavior chosen to the contacts and the categories modal

## Before patch
![skaermbillede 2014-10-06 kl 16 45 41](https://cloud.githubusercontent.com/assets/1738811/4527473/7ac838c6-4d67-11e4-8653-e79c661b1263.png)

## After patch
![skaermbillede 2014-10-06 kl 16 45 30](https://cloud.githubusercontent.com/assets/1738811/4527475/7ad31dd6-4d67-11e4-9513-41c1b6c6f716.png)