Store date inside the embedded firebird database as:
Years as the years since 1900.
Months from 0 to 11.

Change-Id: Ic6269a183261c4c482f91f0d3871b42c54d4b99f
Reviewed-on: https://gerrit.libreoffice.org/28173Reviewed-by: Lionel Elie Mamane <lionel@mamane.lu>
Tested-by: Lionel Elie Mamane <lionel@mamane.lu>