Jquery plugin

Work in progress for 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(...);
});
```

This PR also includes some other enhancements:

1. standardizing the test directories into unit/ and functional/ (like other projects)
2. upgrading to intern 2.1

Everything works except the build (or at least the test for the build), and that's due to a grunt-amd-build problem where a `baseUrl: ".."` interferes with files being placed into the tmp/ directory.  Discussed that with @clmath, who is trying to solve that problem now.
I'm not sure we want that. This would force a dependency on jquery for anyone using this project even though they don't use jquery? I think this is better if we consider this is up to the project using requirejs-dplugins/jquery to add itself the dependency.

(it should be here only as devDependency to be able to test things obviously).