Partner Promo Blocks

[willykaram]

We need to setup blocks that are used to promote our partners. There should be a block for each category of partners -- Tiers (except Lead) and each type of Title Partner. These should be slideshow carousels that rotate through the partners, displaying 2-3 at a time, and randomly rotating through each category.

This will allow us to promote all partners when/as needed. These block will be implemented on the homepage and non-event landing pages (e.g., on the new page and static content pages).

We don't need a block like this for Lead Partners, as these partners will be promoted with a pinned/persistent footer block on all pages (i.e., we're promoting lead partners on all pages) -- see related issue: #64

[willykaram]

I'm moving this to the registration milestone (Wed Apr. 1), as it's not immediately needed on site launch.