refactor opensearch into CSW version specific transforms
refactor opensearch into CSW version specific transforms

bukun/pycsw,ricardogsilva/pycsw,kalxas/pycsw,ingenieroariel/pycsw,ricardogsilva/pycsw,geopython/pycsw,bukun/pycsw,tomkralidis/pycsw,mwengren/pycsw,kalxas/pycsw,ingenieroariel/pycsw,geopython/pycsw,tomkralidis/pycsw,bukun/pycsw,mwengren/pycsw,ocefpaf/pycsw,ricardogsilva/pycsw,geopython/pycsw,ocefpaf/pycsw,benhowell/pycsw,tomkralidis/pycsw,kalxas/pycsw,benhowell/pycsw