Volumes table sorting

This PR allows to sort the "Volumes" table in the storage app. (similar to #439 )

Default sort is by ID. It can be sorted by Name, Size and Format.
![screen shot 2014-10-25 at 10 53 32](https://cloud.githubusercontent.com/assets/1818657/4779281/e9d321d8-5c24-11e4-9eab-2d2f9ec2fce5.png)