First support for md extensions; Package all needed dependencies in the repo

Source/node_modules/core-js/modules/es6.array.join.js

@@ -0,0 +1,12 @@
+'use strict';
+// 22.1.3.13 Array.prototype.join(separator)
+var $export = require('./_export');
+var toIObject = require('./_to-iobject');
+var arrayJoin = [].join;
+
+// fallback for not array-like strings
+$export($export.P + $export.F * (require('./_iobject') != Object || !require('./_strict-method')(arrayJoin)), 'Array', {
+  join: function join(separator) {
+    return arrayJoin.call(toIObject(this), separator === undefined ? ',' : separator);
+  }
+});