Use workflow_id when creating a execution

The field workflow_identifier causes an exception
in the API and in Wallaby the API was moved to
using workflow_id.

Change-Id: I328ce3584f225dc47264a9cba10be7ca788b8e5b

mistraldashboard/workflows/forms.py

@@ -56,7 +56,7 @@ class ExecuteForm(forms.SelfHandlingForm):
 
     def handle(self, request, data):
         try:
-            data['workflow_identifier'] = data.pop('workflow_name')
+            data['workflow_id'] = data.pop('workflow_name')
             data['workflow_input'] = {}
             for param in self.workflow_parameters:
                 value = data.pop(param)