Jquery plugin

Jquery plugin.

Since jquery's model is that every module adds functionality to the $ symbol (i.e. the variable returned by the jquery/core module), I opted to allow listing multiple modules for the plugin, ex:

 ```js
require(["requirejs-dplugins/jquery!attributes/classes,effects"], function ($){
    ...
    $(myNode).addClass("selected");
    $(myNode).animate(...);
});
```

Other things to note:

jQuery code is in jquery/src dir by default, so plugin is mapping to that directory automatically.   Seems a bit weird.

This PR also includes some other enhancements:

1. standardizing the test directories into unit/ and functional/ (like other projects)
2. upgrade to intern 2.1

TODO:  automate build test (webdriver load app.html and check output)

There is actually an issue to remove the dojo dependency (see https://github.com/ibm-js/requirejs-dplugins/issues/4)  but I think the main difference here is that `css!` is actually using the dojo promises in the code while `jquery!` is not using jquery. It's more like an adapter to avoid loading the amd version of jquery if the global version is already loaded. So I think that specifying which version of jquery should be used for the amd version and where it should on the disk is out of the scope of this plugin.