Revert a794cbb..873bb6d

This rolls back to commit a794cbb763eea924bbda392fe5dc2dd3e4807d02.
Revert 873bb6d..29ecfc9

This rolls back to commit 873bb6d258ea50422062ee51b55741e0bfd99f73.
Fix cannot add books problem

shouldPerformSegue — return No is put to the wrong place