Icon for PhotoCollage. Fixes #1191

Icon for PhotoCollage, issue #1191
![photocollage256](https://cloud.githubusercontent.com/assets/7050624/5480726/49ff4ee4-8649-11e4-8bbd-48709ab257df.png)

![photocollage32](https://cloud.githubusercontent.com/assets/7050624/5480724/3feb3ddc-8649-11e4-965c-2c6de6758297.png)