Airlines: Sort by departure date.

The old one was not sorting the items well:

![1](https://cloud.githubusercontent.com/assets/81969/3009584/42d0a492-df00-11e3-8da4-a94ee508c2cf.png)

Here's the new one:

![screen shot 2014-05-18 at 10 48 01 pm](https://cloud.githubusercontent.com/assets/81969/3009586/4be29a18-df00-11e3-82c8-b4ad09faf1a6.png)