Update the print to a672691edbb6ac89ff8ca8c4c770f00c9c0f8503

from
https://github.com/camptocAMP/mapfish-print/tree/c2cgeoportal-1.3
Merge pull request #621 from camptocamp/fix-headers-print

Update the print to a672691edbb6ac89ff8ca8c4c770f00c9c0f8503