Correct URL for Baker & Taylor ContentCafe

Correct URL for Baker & Taylor ContentCafe

This patch updates the URL for image links in ContentCafe

Sponsored by Plano Independent School District, Plano, TX, USA

[RM note: the previous book cover URL was for a varient of Baker
 and Taylor's service that has to do with 'bookstore integration',
 and if I remember correctly, the main difference is that the
 book jacket image had "buy now" text.  The version supplied
 in this patch should work for normal use of ContentCafe.]

Signed-off-by: Galen Charlton <gmcharlt@gmail.com>