[#864] Makes media-list items and media-grid much better looking and more functional

Includes:
- `.media-grid` now stacks nicely on top of each other and each item is it's
own box
- Also `.media-item`s now have a single thing to click on which makes it alot
easier to get to the related item
- Updates to media.less to decrease the amount of noise within the CSS
- Snippets for group_item, organization_item and related_item have been
simplified and a few blocks have been added to them for extendability
- Small fixes to related items index and sub pages