Add typings for the mkpath library

mkpath/mkpath-tests.ts

@@ -0,0 +1,9 @@
+/// <reference path="mkpath.d.ts" />
+import mkpath = require('mkpath');
+
+mkpath('red/green/violet', function (err) {
+  if (err) throw err;
+  console.log('Directory structure red/green/violet created');
+});
+
+mkpath.sync('/tmp/blue/orange', 700);