Bug 11596: report warnings on the about patch if indexing options in koha-conf.xml  are missing

To test:
- Have a clean master install
- Verify that koha-conf.xml contains valid entries for:
  zebra_bib_index_mode and
  zebra_auth_index_mode
- Go to More > About Koha > System information
=> No "Warnings regarding the system configuration"
- Apply the patch
- Go to More > About Koha > System information
=> No "Warnings regarding the system configuration"
- Edit your koha-conf.xml file commenting one or both indexing mode
  entries.
- Go to More > About Koha > System information
=> You get "XML configuration file" warnings for each commented entry.

Sponsored-by: Universidad Nacional de Cordoba
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 11596: (follow-up) ensure all warnings are reported

This patch implements the intent of a patch by Jonathan Druart
that no longer applies cleanly, and ensures that if there are
both warnings about (say) no active currency and missing indexing
mode parameters, that both get reported.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>