refs #11304. Fix issues from testing.

Main issue is around padding of goniometer log inputs. Use zeros rather
than None, as Andrei suggests users may want to apply some but not all of
the goniometer angles in batch.

Code/Mantid/Framework/PythonInterface/plugins/algorithms/WorkflowAlgorithms/CreateMD.py

@@ -189,13 +189,13 @@ class CreateMD(DataProcessorAlgorithm):
         self._validate_inputs()
             
         if len(psi) == 0:
-            psi = [None] * ws_entries
+            psi = [0.0] * ws_entries
             
         if len(gl) == 0:
-            gl = [None] * ws_entries
+            gl = [0.0] * ws_entries
             
         if len(gs) == 0:
-            gs = [None] * ws_entries
+            gs = [0.0] * ws_entries
         
         output_workspace = None
         run_md = None