congress: search by zip

Adds searching by zip code and also handles "from" in the search term.  Searches using a zip code are narrowed down to only people representing that area. 
examples:
    reps from 17089
    representatives from pa

![selection_038](https://cloud.githubusercontent.com/assets/1882892/3110420/3ed79ce0-e6a5-11e3-992b-5942f1c9e49a.png)
![selection_039](https://cloud.githubusercontent.com/assets/1882892/3110424/41532908-e6a5-11e3-9622-ad141785b5f5.png)
@jagtalon @moollaza @russellholt