added command to rotate an image 180 degrees in Writer

Change-Id: I4a1e40f4c3475aceb24edd44691a74372f61b49a
Reviewed-on: https://gerrit.libreoffice.org/30074Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Reviewed-by: Heiko Tietze <tietze.heiko@googlemail.com>
Reviewed-by: jan iversen <jani@documentfoundation.org>
Tested-by: jan iversen <jani@documentfoundation.org>