Abort unauthenticated requests for Firetext inbound SMS

Switches on authentication checks for Firetext inbound SMS callbacks.

This should only be released once Firetext callback URLs have been
updated with authentication details.

app/notifications/receive_notifications.py

@@ -60,10 +60,10 @@ def receive_firetext_sms():
     auth = request.authorization
     if not auth:
         current_app.logger.warning("Inbound sms no auth header")
-        # abort(401)
+        abort(401)
     elif auth.username != 'notify' or auth.password not in current_app.config['FIRETEXT_INBOUND_SMS_AUTH']:
         current_app.logger.warning("Inbound sms incorrect username ({}) or password".format(auth.username))
-        # abort(403)
+        abort(403)
 
     inbound_number = strip_leading_forty_four(post_data['destination'])