Added data URL support for node.js; (#4725)

* Added data URL support for node.js;
Added missed data URL protocol for the browser environment;
Optimized JSON parsing in the default response transformer;
Refactored project structure;
Added `cause` prop for AxiosError instance that refers to the original error if it was wrapped with `AxiosError.from` method;
Added fromDataURI helper;
Added test for handling data:url as an `arraybuffer|text|stream`;

* Added throwing of 405 HTTP error if the method is not GET;

lib/platform/browser/classes/FormData.js

@@ -0,0 +1,3 @@
+'use strict';
+
+module.exports = FormData;

lib/platform/browser/index.js

@@ -3,6 +3,9 @@
 module.exports = {
   isBrowser: true,
   classes: {
-    URLSearchParams: require('./classes/URLSearchParams')
-  }
+    URLSearchParams: require('./classes/URLSearchParams'),
+    FormData: require('./classes/FormData'),
+    Blob: Blob
+  },
+  protocols: ['http', 'https', 'file', 'blob', 'url']
 };