Pad study (and lab) images

[mekline]

No description provided.

[mekline]

Currently, labs are asked to limit file sizes on upload, but we don't enforce the size at which they are displayed. This means that the study search page is 'ragged' because of differing heights, and some views render poorly or revert to the actual size: see this mobile view (https://lookit.mit.edu/studies/early-childhood-cognition-lab/):

Solution: For all image types (study, lab banner, lab badge), define a standard aspect ratio. If provided image does not match this, pad with background color to fit it in the correct shape of box. Ensure that boxes are displaying at correct sizes on mobile, lab detail page, etc.