Reformats Dashboard links in sorted, tabular form

This PR should resolve issue #278.

Under each activity subsection, classes are now sorted first by Organization name and then by Start Date.  The formatting of the links has been changed to a tabular form showing the relevant information:

![screen shot 2013-08-27 at 1 04 04 pm](https://f.cloud.github.com/assets/1851667/1037659/f149d4e4-0f53-11e3-90ce-8236d9ce49f4.png)