Made appearance closer to the stock Photos app.

I got rid of the lines between the albums. Also I put some padding around the
album thumbnails.

See this screenshot for the improvements:
http://monosnap.com/image/wcBd9YW65Y0AWFAVhUy0xgLoUx0pV5

I have created a similar pull request for the original ELCImagePickerController
project: https://github.com/B-Sides/ELCImagePickerController/pull/98