add client.getXliff

wip For: IBM-Cloud#118

lib/client.js

@@ -556,6 +556,32 @@ class Client {
     });
   }
 
+  /**
+   * Get XLIFF for this instance
+   * @param {Object} opts
+   * @param {String} opts.sourceLanguageId - source ID
+   * @param {String} [opts.targetLanguageId] - defaults to opts.sourceLanguageId
+   * 
+   * @param {Function} [cb] - callback (or else will return Promise)
+   */
+  getXliff(opts, cb) {
+    opts = utils.fixArgs(arguments);
+    if((cb = arguments[1])) {
+      return utils.depromise(this.getXliff(opts), cb);
+    }
+
+    opts.serviceInstanceId = opts.serviceInstanceId || this.serviceInstance;
+    // opts.sourceLanguageId = opts.sourceLanguageId;
+    opts.targetLanguageId = opts.targetLanguageId || opts.sourceLanguageId;
+
+    // this is an odd one because it's not JSON data in return.
+    // so, we cannot use restCall() (yet!)
+    // this.restCall("partner.getXliffFromBundles", opts, cb);
+
+    return this.gp.swaggerClient
+      .then(client => 
+        client.apis.partner.getXliffFromBundles(opts));
+  }
 }
 // const debugURL = false;
 // const debugREST = false;