add API endpoint for mails and tests

core/mail/api_v2.py

@@ -0,0 +1,20 @@
+from rest_framework import routers, viewsets, serializers
+
+from mail.models import Email
+
+
+class EmailSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Email
+        fields = '__all__'
+
+
+class EmailViewSet(viewsets.ModelViewSet):
+    serializer_class = EmailSerializer
+    queryset = Email.objects.all()
+
+
+router = routers.SimpleRouter()
+router.register(r'mails', EmailViewSet, basename='mails')
+
+urlpatterns = router.urls