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)

> as I find my alternate proposal cleaner and I don't see any drawback* I still prefer it, and @clmath seems to as well

OK, so it mainly comes down to a philosophical issue for you, that you find it wrong for requirejs-dplugins to list jquery as a dependency.

The main drawback of removing the dependency is that some people will likely think the plugin is broken, and every few months someone will file a ticket like:

* jquery plugin broken: it gets 404 errors about not being able to find files
* jquery plugin doesn't work unless you have a `<script>` tag including jquery; this should not be necessary.

If you are ready to handle those tickets and those unhappy users, I don't really care if we remove the dependency.