Prevent squashing of preview images in article list

Hi, these changes stop the squashing of preview images in the article list, plus also adds padding between the image and description text. Feel free to ignore this if the stretched look is the preferred design, and sorry for not following convention and starting with an issue first (... let me know if you want one created and I can do things in reverse 🙂 ).

Another approach might be to take a crop of the largest area in the center of the image which fills the allocated space on the right, perhaps with some rounded corners. To my eyes the stretching looks odd.

Before

After