Revert "Check if we should redirect to some other content in a model."

This reverts commit 993bf1876a497a22487131f14f4b852baaddfba2.
Revert "Opening a book redirects to editing the first module in the book."

This reverts commit 5ea40c05060800fcb1794dcc81b04f7b001d21ce.
Explicitly find first module and edit book in context of opf.