Fix test.

Author: federicotdn

data/test_trackers/tracker_moodbot.json

@@ -32,7 +32,6 @@
   "events": [
     {
       "timestamp": 1517821726.211031,
-      "metadata": {},
       "event": "action",
       "name": "action_listen",
       "policy": null,
@@ -69,15 +68,13 @@
     },
     {
       "timestamp": 1517821726.200373,
-      "metadata": {},
       "event": "action",
       "name": "utter_greet",
       "policy": null,
       "confidence": null
     },
     {
       "timestamp": 1517821726.211038,
-      "metadata": {},
       "event": "action",
       "name": "action_listen",
       "policy": null,
@@ -114,15 +111,13 @@
     },
     {
       "timestamp": 1517821726.209908,
-      "metadata": {},
       "event": "action",
       "name": "utter_happy",
       "policy": "policy_1_KerasPolicy",
       "confidence": 0.8
     },
     {
       "timestamp": 1517821726.211042,
-      "metadata": {},
       "event": "action",
       "name": "action_listen",
       "policy": "policy_2_MemoizationPolicy",