This is different to the old categories drop down, because that also
included meta-categories of "Whats New" and "Recently Updated". Given
we now show them on the first page, this categories screen can do away
with them.
Each category entry loads a few apps to show to the user.
Note: The "View all" button next to each category doesn't currently
go anywhere. It will soon be hooked up to an app list that is filtered
to the selected category.