Setup library and tests to run with either es6 or es5

.babelrc

@@ -0,0 +1,12 @@
+{
+  "presets": [
+
+    ["env", {
+      "targets": {
+        "node": "4"
+      }
+    }],
+    "stage-0"
+  ],
+  "plugins": []
+}

.travis.yml

@@ -1,5 +1,13 @@
 language: node_js
-node_js:
-- '4'
-- '6'
-- '8'
+nvm:
+
+matrix:
+  include:
+  - node_js: "4"
+    script: npm run test-es5
+  - node_js: "6"
+    script: npm run test-es5
+  - node_js: "8"
+    script: npm run test-es6
+  - node_js: "10"
+    script: npm run test-es6

babel.config.js

@@ -1,7 +1,14 @@
 const presets = [
   [
-    "@babel/env",
+    [
+      "env",
+      {
+        targets: {node: "4"}
+      }
+    ],
+    "stage-0"
   ],
 ];
+const plugins = ["transform-object-rest-spread"];
 
-module.exports = { presets };
+module.exports = {presets, plugins};

cloudinary.js

@@ -1 +1 @@
-module.exports = process.versions.node[0] === '4' ? require('./lib-node4/cloudinary') : require('./lib/cloudinary');
+module.exports = Number(process.versions.node[0]) < 8 ? require('./lib-es5/cloudinary') : require('./lib/cloudinary');