Chen calculate distance

https://trello.com/c/e7RgqDWh/49-as-a-user-i-can-calculate-distance-and-time-between-places

![calculate distance and time for a trip](https://cloud.githubusercontent.com/assets/3759510/5144553/5f7f5254-7169-11e4-8bbd-da0ca6eac23b.gif)