Bug 4460: Amazon's AssociateID tag not used in links so referred revenue lost

Bug 4460: Amazon's AssociateID tag not used in links so referred revenue lost

Reworking based on output of:
git grep "gp\/reader"
Additionally, some changes might be in order though gp/reader works.
https://affiliate-program.amazon.com/help/topic/t64/a1
suggests using dp
A dp was discovered, so that part of the URL was left unchanged.
The "/ref..." part was changed to just an Amazon tag ("?tag={AAT}")
if defined.

TEST PLAN
---------
 1) Added:
     "100 years of Canadian foreign policy /
      edited by Robert Bothwell and Jean Daudelin."
 2) Added a second book with the word foreign in the title.
 3) Waited for reindex
 4) Checked out the Canadian foreign policy book.
 5) Applied patch
 6) Made sure that:
    - AmazonAssocTag was set to TEST (easy to notice)
    - AmazonCoverImages was set to 'Show'
    - OPACAmazonCoverImages was set to 'Show'
 7) Searched intranet for 'foreign' to find the detail page
    -- hovering over picture shows URL with ?tag=TEST in it.
 8) Went to the OPAC Detail page
 9) Toggling OPACURLOpenInNewWindow, confirmed that URL for
    the picture contained ?tag=TEST in it.
10) Logged into the OPAC
11) Confirmed the URL in the checked out list on your summary
    page contained ?tag=TEST in it.
12) Confirmed the URL in the checked out list on your reading
    history page contained ?tag=TEST in it.
13) Confirmed links worked (went to expected page)
14) run koha qa test tools

Followed test plan. Works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer  <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>