Fill 'wf_name' task_db field

* Now wf_name is shown correctly in task CLI commands

Closes-bug: #1388013

Change-Id: I8a07c4f377e44153905c0b93da5dfc1fef518337

mistral/engine1/commands.py

@@ -100,7 +100,8 @@ class RunTask(EngineCommand):
             'input': None,
             'in_context': None,
             'output': None,
-            'runtime_context': None
+            'runtime_context': None,
+            'wf_name': exec_db.wf_name
         })
 
     def _run_task(self):

mistral/tests/unit/engine1/test_default_engine.py

@@ -93,6 +93,7 @@ class DefaultEngineTest(base.DbTestCase):
 
         task_db = exec_db.tasks[0]
 
+        self.assertEqual('wb.wf1', task_db.wf_name)
         self.assertEqual('task1', task_db.name)
         self.assertEqual(states.RUNNING, task_db.state)
         self.assertIsNotNone(task_db.spec)