Make Elemental.load() accept HTML with multiple root nodes.

This allows you to do:

    Elemental.load('<div data-behavior="hi"></div>  <div data-behavior="bye"></div>');

Before you could only have a data-behavior on the only root level element.

If you upgrade to jQuery 1.8, then line 32 of src/elemental.js could become:

    var $selector =  $('[data-behavior]', container).andSelf('[data-behavior]');