Picasso options in SliderLayout

[khrizt]

Hi,

I'm using your library to display sliding images and I'm wondering if it would be possible to add custom Picasso properties to the sliding images. I'm especially interested in adding the onlyScaleDown method to the picasso loader so big images don't get resized up. Would that be possible?

Thanks

[khrizt]

I've sent a pull request with these changes

#194