Improve addShows trending page by using less memory and loading quicker.

The trending page shows approx. 500 images and typically, the size of fetched images were 1000 x 1500 pixels. The browser was relied on to reduce the images while rendering to 186 x 273 pixels. The result used a *lot* of memory, bandwidth, time, render processing, and server resources to populate the page so those issues have been eased by fetching smaller 300 x 450 pixel images instead.
Merge pull request #877 from JackDandy/ImproveAddTrending

Improve addShows trending page by using less memory and loading quicker.