Use a custom pixel projection in lubis viewer

This PR fixes the inital bbox of the viewer using a more logical custom pixel projection.

Before: http://mf-chsdi3.dev.bgdi.ch/ltjeg/wsgi/rest/services/luftbilder/MapServer/ch.swisstopo.lubis-luftbilder_schwarzweiss/19280250112499/extendedHtmlPopup?lang=fr

After: http://mf-chsdi3.dev.bgdi.ch/ltteo/wsgi/rest/services/luftbilder/MapServer/ch.swisstopo.lubis-luftbilder_schwarzweiss/19280250112499/extendedHtmlPopup?lang=fr