"Promoted Blocks" needs a dedicated configuration page

Problem/Motivation

The promoted blocks feature is awesome, except that one cannot come back and easily edit this list. (I had to use my browser history to get there.)

Steps to reproduce

Once you have added promoted blocks, there is no easy way to get back to the page to re-configure the needed blocks.

Proposed resolution

* Add a persistent link to the footer of the promoted blocks interface
* Add configuration to the LB+ configuration page as well