ODF TC decided to rename the element to meta:creator-initials, so adapt
the import so it can read this in addition to the 2 element names
produced by current and past LO versions.

Also add a test.

Unfortunately it turned out that the ODF validator had a bug in checking
character data in foreign elements, which is triggered by the test
document, see https://issues.apache.org/jira/browse/ODFTOOLKIT-475
... so update the validator jar as well.

Change-Id: I1de1e8772b41f8937f043d9a0d150e169f25ffd4
Reviewed-on: https://gerrit.libreoffice.org/53979Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
(cherry picked from commit b09889a1)
Reviewed-on: https://gerrit.libreoffice.org/54001Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
(cherry picked from commit 1a8fcf5c)