Bug 23538: (QA follow-up) Group system preferences into one entry

Bug 23538: (QA follow-up) Group system preferences into one entry

This makes the new perferences EmailPatronRegistrations and EmailAddressForPatronRegistrations
follow a little more closely the pattern set by the very similar
EmailPurchaseSuggestions and EmailAddressforSuggestions.

* Group both preferences into one entry
* Add line break between preferences
* Switch branch for library in pull down

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>