Add slideshow permissions to application.

#6060 
After the fix we get the slides permissions in the vsite permissions, and changing it effect the creation of the slide and the existence of the "add slide" link.
![selection_086](https://cloud.githubusercontent.com/assets/99186/2943195/d94eb5da-d9bf-11e3-97ce-f9db7daa5075.jpeg)
![selection_087](https://cloud.githubusercontent.com/assets/99186/2943196/dafbd7a0-d9bf-11e3-9390-f13f8bc31243.jpeg)
![selection_088](https://cloud.githubusercontent.com/assets/99186/2943201/072d00c4-d9c0-11e3-9d37-f90f5304b031.jpeg)