Make OpenLibrary the default added content provider

Make OpenLibrary the default added content provider

OpenLibrary is a better choice than Amazon for added content out of the box
because:

1) The OpenLibrary added content handler provides cover images +
tables of content, whereas the Amazon added content handler only
provides cover images.

2) The terms of use for OpenLibrary content are much friendlier than
the Amazon "Product Advertising API".

We discussed this back in mid-2009: http://markmail.org/message/csx2hl6aleznapga

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_0@17531 dcc99617-32d9-48b4-a31d-7c20da2025e4