Bug 8262: explicitly warn that database admin account cannot create lists

Since kohaadmin has no borrower number, it cannot create lists.
A database error is logged, but the user is not notified.
This patch alerts the user.

In the incidental case that a normal user gets a database error,
they are notified too that the list could not be created.

Test plan (for prog and bootstrap):
* This patch should be applied on top of 9032 patches.
* Login as as the database admin user
* Create a list in opac and staff. Check the message.
* Login as a normal user.
* Force a database error on list creation (I renamed category
  in the table with alter table change column..)
* You should have a different error message.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jesse Maseto <jesse@bywatersolutions.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works as described, passes tests and QA script.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 8262: (follow-up) correct comment

There is no guarantee that the database admin user
is going to be called "kohaadmin".

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