Support nested menus (nested uls)

[chrisolof]

Resolves #4.

I noticed in the less file a mix of tab and double-space indentation. Couldn't quite determine the predominate pattern so I went with double-space indentation.

[VPenkov]

Chris, thank you for your contribution.
My intent is to use classes for lower-level menus instead of nested selectors.

I will be releasing a new version soon enough. Some of your code will be used and some will be somewhat refactored.

[jmvtrinidad]

Support for level 3 sub-menu will be awesome! 😄

[alexcamlo]

Hi,

Do you have an example of the index.html to work with this multi-level menu modification?
I have tried something like this but doesn't work

<li><a href="#">Shop</a>
    <ul>
        <li><a href="">hola1</a></li>
        <li><a href="">hola2</a></li>
        <li><a href="">hola3</a></li>
        <li><a href="">hola4</a></li>
        <li><a href="">hola5</a></li>
    </ul>
</li>