Update user guide copyright to 2013
Update user guide copyright to 2013

fiuba08/robotframework,waldenner/robotframework,ldtri0209/robotframework,waldenner/robotframework,ldtri0209/robotframework,ldtri0209/robotframework,waldenner/robotframework,waldenner/robotframework,ldtri0209/robotframework,waldenner/robotframework,fiuba08/robotframework,fiuba08/robotframework,fiuba08/robotframework,ldtri0209/robotframework,fiuba08/robotframework