metadata fields specified in the datacard should be automatically in virtualdb _meta

[cmatKhan]

repositories:
  BrentLab/callingcards:
    regulator_locus_tag:
      field: regulator_locus_tag
    regulator_symbol:
      field: regulator_symbol

there should be no need for regulator_locus-tag and regulator_symbol b/c htey are already identified as metadata fields in the datacard for callingcards