Squashed 'cwltool/schemas/' changes from ca31436..c4cfafb

c4cfafb Make draft-2 SchemaDef name optional.

git-subtree-dir: cwltool/schemas
git-subtree-split: c4cfafb

Author: Peter Amstutz

draft-2/CommonWorkflowLanguage.yml

@@ -982,7 +982,7 @@ $graph:
       specializeTo: "#CommandLineBinding"
   fields:
     - name: name
-      type: string
+      type: ["null", string]
       doc: "The type name being defined."