Update featured review criteria

[js0mmer]

Currently, it seems to grab the latest review for the professor. It some cases, this review may have no content.

Example:

We should update criteria so that it will always feature a review with content. In the case of no review that meets that criteria, we can display an N/A message. We might also want to show reviews with the highest score too instead of the latest or have some other sort of algorithm/criteria for determining what should be featured.