Updating some old icons from square to circle

 Getting in the basics of Inkscape practice!

Amule
![1](https://f.cloud.github.com/assets/5920259/2527514/e9327574-b505-11e3-8ac7-48e6365950cc.png)

Aqualung
![2](https://f.cloud.github.com/assets/5920259/2527515/e9327a88-b505-11e3-88bc-2488209cd51b.png)

Audiobook
![audiobook](https://f.cloud.github.com/assets/5920259/2529028/5328664a-b516-11e3-89d5-7c413b51ee6f.png)

Boot
![3](https://f.cloud.github.com/assets/5920259/2527516/e93d0372-b505-11e3-85bd-27624f4022a2.png)

Cog
![0](https://f.cloud.github.com/assets/5920259/2528921/e8f8a100-b514-11e3-9e75-c49523d43db0.png)