Minor changes: made make.js executable and updated CONTRIBUTING.

You can now use make.js without explicitly specifying node:

	./make.js test

I removed the note about hard-tabs and jshint.js because it was no
longer true.

CONTRIBUTING.md

@@ -31,7 +31,7 @@ many people contributed. —[idiomatic.js](https://github.com/rwldrn/idiomatic.j
 
 ### Whitespace:
 
-* We use hard tabs everywhere except for `src/stable/jshint.js`. It's annoying, we know.
+* We use hard tabs everywhere.
 * [Smart tabs](http://www.emacswiki.org/SmartTabs) are okay.
 * Use one space after `if`, `for`, `while`, etc.
 * Use one space after `function` for anonymous functions but not for named functions:

make.js

@@ -1,3 +1,5 @@
+#!/usr/bin/env node
+
 "use strict";
 
 require("shelljs/make");