Updated metadata and uncertainty files to test what happens if one decorrelates the luminosity uncertainty

Author: enocera

nnpdf_data/nnpdf_data/commondata/ATLAS_WPWM_8TEV/metadata.yaml

@@ -77,6 +77,10 @@ implemented_observables:
     file: kinematics.yaml
 
   data_uncertainties: [uncertainties.yaml]
+  variants:
+    lumiunc:
+      data_uncertainties:
+      - uncertainties_lumiunc.yaml
 
   data_central: data.yaml