LP#1499537 Fixed kpac.xml caching problem

LP#1499537 Fixed kpac.xml caching problem

The EGKPacLoader.pm file caches the kpac.xml file in a global variable.
However, we are using multiple kpac.xml files, which means sometimes the
incorrect kpac.xml file is cached. This causes a problem becuase the
owner attribute of the of the layout element specifies which OU to load
the grid of images for.  When using separate kpac.xml files there is
only one layout element per file, and if the inccorect kpac.xml file is
loaded for an OU, then no layout will be generated resulting in the
missing images.

Signed-off-by: Liam Whalen <liam.whalen@bc.libraries.coop>