npm install + git add -a

node_modules/axios/lib/helpers/toURLEncodedForm.js

@@ -0,0 +1,18 @@
+'use strict';
+
+var utils = require('../utils');
+var toFormData = require('./toFormData');
+var platform = require('../platform/');
+
+module.exports = function toURLEncodedForm(data, options) {
+  return toFormData(data, new platform.classes.URLSearchParams(), Object.assign({
+    visitor: function(value, key, path, helpers) {
+      if (platform.isNode && utils.isBuffer(value)) {
+        this.append(key, value.toString('base64'));
+        return false;
+      }
+
+      return helpers.defaultVisitor.apply(this, arguments);
+    }
+  }, options));
+};