Fixes #1619

The latest version (1.5.0) of `less.js` conflicts with `require.js` (if loaded before `require.js`), causing the following error:

    Uncaught TypeError: Object function require(a){return window.less[a.split("/")[1]]} has no method 'config'

It seems that this is only an issue with the minified version (`less-1.5.0.min.js`) because the minified JavaScript is not wrapped in an anonymous closure. Adding `function(){` to the beginning and `}())` to the end of the minified file.