[gh-552] Rework Menu Block css in unl_wdn theme

Need to get rid of this:

.block-menu-block .content > ul > li > a {display: none;}

When I was first creating Menu Blocks I started them at the wrong level and wanted to hide the root: (Inspect element:) http://payroll.unl.edu/policies/list

The real solution is to start the Menu Block one more level down.