Allow for providing existing images as a model, or leaving it for the client to download & cache them

[senart]

Rationale

Right now users can add image urls by setting the contentImageURLs array with strings.
What if they want to cache those images or download them beforehand?

Possible Solution

The contentImageURLs might be replaced with a dataSource and delegates, allowing for the model objects to be provided when they are needed, much like Apple does with their UITableView & UICollectionView classes.