change serializer for user_api

JoinTheCityREST/app/User/serializers.py

 from django.contrib.auth.models import User
 from rest_framework import serializers
+from app.API.serializers import APISerializer
 from app.Event.serializers import EventSerializer
 from app.User.models import UserFriendship, UserAPI, UserEvent, UserEventRequest
 
@@ -20,9 +21,11 @@ class UserEventRequestSerializer(serializers.HyperlinkedModelSerializer):
         fields = ('url', 'event', 'created_by')
 
 class UserAPISerializer(serializers.HyperlinkedModelSerializer):
+    api = APISerializer()
+
     class Meta:
         model = UserAPI
-        fields = ('url','api')
+        fields = ('api', )
 
 class UserEventSerializer(serializers.HyperlinkedModelSerializer):
     class Meta: