Cosmetic changes for nicer figures

[evevkovacs]

If you are submitting a PR for a validation test (either adding a new one or updating an existing one), please post a link to the DESCQA web interface for the test you are submitting.
Added some cosmetic changes to allow for making better figures. See [here] (https://portal.nersc.gov/project/lsst/descqa/v2/?run=2019-09-19_4) for a test run.

[evevkovacs]

@yymao See test result for example of code with object catalog. Other issues should be fixed.

[evevkovacs]

@yymao Just caught your last comments. The commented line has been removed. I also removed the exception clause. I have already checked that the catalog has ra and dec so there is no reason for the call to get_sky_area to fail, and it is safe to remove the exception.

[yymao]

@evevkovacs thanks! I would then suggest that we reorganize the logic a little bit for lines 152-165. In particular, checking ra/dec existence is more relevant for sky area, not for light cone. See my inline suggestion.

[yymao]

thanks!