Bug 14571: using_https check for ssl connections doesn't work in some situations

 Bug 14571: using_https check for ssl connections doesn't work in some situations

To test:

* turn on Amazon images for result and detail in the OPAC
* do a search that will result in an Amazon image being displayed on the
  result page
* inspect the cover image that is returned on the result page, it should
  be using a https://images-na... Amazon URL.
* click through to the detail for that item
* inspect the cover image that is returned on the detail page, it should
  be using a https://images-na... Amazon URL.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>