Add VINGETTE and VING_MIN to headers

[gmegh]

Currently the butler will not define visits unless the images have VINGETTE and VING_MIN in the headers, which then are used to define can_see_sky? in the exposure record

[jchiang87]

Is there any documentation on what these keywords mean, how the values are ascertained etc. that you can point to please?

[jchiang87]

As discussed in slack, we don't need to add these keywords for the LsstCamSim instrument, which was added in #473 . However, we neglected to make that camera the default and we didn't remove LsstCam. That's now done in #503 . I've confirmed that butler define-visits works with raw files created using LsstCamSim.