Migrate past max-walk and remove references to it

This removes walk time from html, js, and python. Scala may still need some work. It also extends arrive_by_time into python.

Migration included, so reprovisioning is necessary.

![screen shot 2014-11-17 at 4 06 45 pm 2](https://cloud.githubusercontent.com/assets/1977405/5077695/dbb58e86-6e73-11e4-9dd0-03f851e53e39.png)