Added scores, added jackknife errors to config file

[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 chisq/dof score to test as validation criteria. score is computed for each plot, reported in summary text and average score is computed for pass/fail. pass/fail limit is optional input..defaults to 2.
A more stringent score would be to demand that all subplots pass the criterion instead of just the average. See
https://portal.nersc.gov/project/lsst/descqa/v2/?run=2018-04-12_45&catalog=proto-dc2_v4.0_test&right=2018-04/2018-04-12_45/Nz_i_Coil2004_maglim/proto-dc2_v4.0_test/Nvsz_LSST_i.txt