#3949: Revert to using book_cover_thumb image style. Make it slightly larger.
#3949: Use book_cover_thumb for real this time
#3949: Set height on book_cover_thumb.
#3949: Remove unneeded reordering and filling in of missing data.
Merge pull request #4276 from openscholar/3949-book_cover_thumb_3.9

Reuse book cover thumb image style