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/helpers/toFormData.js

@@ -1,7 +1,7 @@
 'use strict';
 
 var utils = require('../utils');
-var envFormData = require('../defaults/env/FormData');
+var envFormData = require('../env/classes/FormData');
 
 function isVisitable(thing) {
   return utils.isPlainObject(thing) || utils.isArray(thing);