Bug 8679 [REVISED] Remove usage of Amazon API

Bug 8679 [REVISED] Remove usage of Amazon API

This patch removes the AmazonReviews and AmazonSimilarItems
features from the OPAC and staff client. With on Amazon
feature remaining, cover images, the *AmazonEnabled preference
is also removed in favor of checking the *AmazonCoverImages
preference. Two other system preferences, AWSAccessKeyID and
AWSPrivateKey are removed as they were required only by the
removed features.

Handling of book cover images from Amazon is unchanged.

Signed-off-by: Nicole C. Engard <nengard@bywatersolutions.com>

Turned on amazon covers in opac and staff client and all
worked as expected. Then tested to make sure other cover image
services still worked and they do.

Signing off.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>