Theme generator.

Work in progress, will probably end up in tools or something like that.
Problem is that less.js APi is not documented so I have to digg in the source.
It also requires less 2.0.

Allow you to easy generate a theme for the notebook. It should even be able to watch for file change and recompile on the fly.

With 
```
i= setInterval( 
  function(){
    $('head>link:nth(4)').attr('href',"/static/style/style.min.css?v="+Date()); console.log(Date())}
  , 4000)
```
it allows the css to be live reloaded in the notebook, without refreshing the page, which is nice to play with css..