title: SSHOperator showing "No Status" after manual trigger
body: <p>I am new to airflow and I have written a simple SSHOperator to learn how it works.</p>
  
  <pre><code>default_args = {
  'start_date': datetime(2018,6,20)
  }
  
  dag = DAG(dag_id='ssh_test', schedule_interval = '@hourly',default_args=default_args)
  
  sshHook = SSHHook(ssh_conn_id='testing')
  
  t1 = SSHOperator(
      task_id='task1',
      command='echo Hello World',
      ssh_hook=sshHook,
      dag=dag)
  </code></pre>
  
  <p>When I manually trigger it on the UI, the dag shows a status of running but the operator stays white, no status.</p>
  
  <p>I'm wondering why my task isn't queuing. Does anyone  have any ideas? My airflow.config is the default if that is useful information. </p>
  
  <p>Even this isn't running</p>
  
  <pre><code>dag=DAG(dag_id='test',start_date = datetime(2018,6,21), schedule_interval='0 0 * * *')
  runMe = DummyOperator(task_id = 'testest', dag = dag)
  </code></pre>