add requirements-dev.txt since needed by travis
add requirements-dev.txt since needed by travis

tomkralidis/pycsw,mwengren/pycsw,ocefpaf/pycsw,ckan-fcd/pycsw-fcd,tomkralidis/pycsw,bukun/pycsw,kevinpdavies/pycsw,kalxas/pycsw,rouault/pycsw,kalxas/pycsw,PublicaMundi/pycsw,ricardogsilva/pycsw,benhowell/pycsw,bukun/pycsw,mwengren/pycsw,geopython/pycsw,geopython/pycsw,ingenieroariel/pycsw,ricardogsilva/pycsw,bukun/pycsw,kalxas/pycsw,benhowell/pycsw,ingenieroariel/pycsw,ricardogsilva/pycsw,tomkralidis/pycsw,ckan-fcd/pycsw-fcd,kevinpdavies/pycsw,rouault/pycsw,geopython/pycsw,ocefpaf/pycsw,PublicaMundi/pycsw