title: Fetch only albums in a PHCollectionList
body: <p>A <code>PHCollectionList</code> is a folder that could contain any number of albums and/or folders. I am currently fetching the collections within the list via <code>PHCollection.fetchCollectionsInCollectionList(list, options: nil)</code>.</p>
  
  <p>This could return objects of type <code>PHAssetCollection</code> or <code>PHCollectionList</code>. I am only interested in knowing of the <code>PHAssetCollection</code>s in that list. The docs state you can apply a filter predicate using the fetch options in order to return a subset of the data, but I don't see how I would use that in order to only get albums. How do you use <code>PHFetchOptions</code> in order to return only <code>PHAssetCollection</code>s in a given <code>PHCollectionList</code>?</p>