test: use RC instance for all visual recognition integration tests

Author: dpopp07

test/integration/test.visual_recognition.js

@@ -20,8 +20,8 @@ describe('visual_recognition_integration', function() {
 
   before(function() {
     visual_recognition = new watson.VisualRecognitionV3(
-      Object.assign({}, auth.visual_recognition.v3, {
-        version: '2018-03-19',
+      Object.assign({}, auth.visual_recognition_rc.v3, {
+        version: '2018-10-01',
       })
     );
     nock.enableNetConnect();