optimize rtc error message and fix its tests

- read response body error first
- add rpqId property
- always try to delete rtc app after tests

Author: lihsai0

qiniu/rtc/app.js

@@ -23,7 +23,8 @@ function get(credentials, options, fn) {
             if (res.statusCode != 200) {
                 var result = {
                     code: res.statusCode,
-                    message: res.statusMessage
+                    message: resultObject.error || res.statusMessage,
+                    reqId: res.headers['x-reqid']
                 };
                 fn(result, null);
             } else {
@@ -59,7 +60,8 @@ function post(credentials, options, data, fn) {
             if (res.statusCode != 200) {
                 var result = {
                     code: res.statusCode,
-                    message: res.statusMessage
+                    message: resultObject.error || res.statusMessage,
+                    reqId: res.headers['x-reqid']
                 };
                 fn(result, null);
             } else {

test/rtc.test.js

@@ -26,6 +26,13 @@ describe('test rtc credentials', function () {
         maxUsers: 10,
         noAutoKickUser: true
     };
+
+    after(function (done) {
+        qiniu.app.deleteApp(appId, credentials, function () {
+            done();
+        });
+    });
+
     // eslint-disable-next-line no-undef
     describe('test create app', function () {
         // eslint-disable-next-line no-undef