Piper/restframework 3.0.0 compatibility

### What is the problem / feature ?

Hard dependency on DRF 2.4.4

### How did it get fixed / implemented ?

Changed to >= 2.4.4

### How can someone test / see it ?

Code


*Here is a cute animal picture for your troubles...*

![christmas-balbinka-l](https://cloud.githubusercontent.com/assets/824194/5446826/81fbc7b0-8481-11e4-87ca-aef2468be9af.jpg)