Add featured projects to homepage

[bradweikel]

Add a fourth column to the "Get Involved!" section of the home page template called “Featured Project” with pointers to both the abqvotes.org and imagineabq.org. If you want to use fancy logos instead of regular text point to the sites:

https://github.com/codeforabq/abqvotes/blob/master/images/abqvotes_logo.png
https://github.com/codeforabq/imagine-abq/blob/master/Logos/imagine-banner-black.png

(transplanted from https://github.com/codeforabq/Brigade-Brain/issues/3)