Nlg template fix (#121)

* fix nlg template

* fix user nlg template issue

convlab2/nlg/template/multiwoz/manual_user_template_nlg.json

@@ -26,7 +26,6 @@
             "I ' m looking for a #ATTRACTION-INFORM-TYPE# type attraction .",
             "A #ATTRACTION-INFORM-TYPE# type of attraction .",
             "Do you have any #ATTRACTION-INFORM-TYPE# attractions",
-            "Okay , are there any #ATTRACTION-INFORM-TYPE#s in the centre ?",
             "How about a #ATTRACTION-INFORM-TYPE# ?",
             "I was also wondering if you would be able to help me find a place to go to see some great #ATTRACTION-INFORM-TYPE# .",
             "I prefer something related to #ATTRACTION-INFORM-TYPE#",