Add "show more" link to the school finder.

# Changes
- Adds "show more" link to the school finder. Fixes #3326.

References DoSomething/lofi-schools-flask#2 and DoSomething/lofi-schools-flask#3.

# Screencast
![screen recording 2014-11-05 at 05 03 pm](https://cloud.githubusercontent.com/assets/583202/4926962/9b46ca94-6537-11e4-8126-f74ad94d67f2.gif)