Add tests for new features

I wanted to add test for loading from array, like code bellow.
But it seems to have some problems, I'll see it later.

```
asyncTest("loading from array", function () {
    expect(5);

    head
    .js(
        [{
            // warning: if label is 'jquery', seems like the jQuery object is assigned instead of a simple label
            jq: 'http://code.jquery.com/jquery-1.9.1.min.js',
            options: {
                async: true,
                callback: function () {
                    ok(!!jQuery, "Label: ready('jq')");
                }
            }
        },
        {
            underscore: 'http://underscorejs.org/underscore-min.js',
            options: {
                async: true,
                callback: function () {
                    ok(!!_, "Label: ready('underscore')");
                }
            }
        }], function() {
            ok(!!jQuery, "Callback: jQuery");
            ok(!!_,      "Callback: underscore");
        }
    )
    .ready(['underscore'], function () {
        ok(!!_, "Label: ready('underscore')");
    });

});
```