Allow astropy.io.fits in lieu of pyfits
(#488)
Use mock pyfits version number for astropy.io.fits
Make YAML dict tests in test_config_value optional.
Add astropy option to INSTALL and HISTORY
(#488)
typo
(#488)
Merge pull request #489 from GalSim-developers/#488

#488 Support astropy.io.fits