[UP-4298]  Add a quick link to the admin portlet for configuring the the...

...me.  Displays config in a lightbox.

https://issues.jasig.org/browse/UP-4298

Screens:
Link:
![up-4298_link](https://cloud.githubusercontent.com/assets/7871998/5055207/4826b3f0-6c1d-11e4-80a7-6241781a936b.png)

Lightbox:
![up-4298_lightbox](https://cloud.githubusercontent.com/assets/7871998/5055210/5136f0cc-6c1d-11e4-8311-9602fc2ae859.png)

Is `PortletAdministrationHelper` the right component to be an authority on how to get the URL to the `dynamic-respondr-skin` portlet?