add unknown-option-value as an error message to be ignored by pylint

.pylintrc

@@ -71,6 +71,7 @@ disable=fixme,              # disabled as TODOs would show up as warnings
     no-else-return,     # relax "elif" after a clause with a return
     docstring-first-line-empty, # relax docstring style
     import-outside-toplevel,
+    unknown-option-value,
 
 
 [REPORTS]