Added atob and btoa for node

snippets/atob.md

@@ -0,0 +1,13 @@
+### atob
+
+Decodes a string of data which has been encoded using base-64 encoding.
+
+Create a `Buffer` for the given string with base-64 encoding and use `Buffer.toString('binary')` to return the decoded string.
+
+```js
+const atob = str => new Buffer(str, 'base64').toString('binary');
+```
+
+```js
+atob('Zm9vYmFy'); // 'foobar'
+```