Improve content of external reference catalogs

Looking at the content of the external reference catalogs available at NCSA and accessible via astrometry_net_data: sdss-dr9-fink-v5b and 2mass.20130404, I see that none of them provide errors on the source coordinates and the 2mass one does not provide the error on the flux. Accurate astrometry and photometry should take into account the errors from the reference catalogs.