Merge feature SOL-20

This is a pull request to merge the SOL-20 feature (https://openedx.atlassian.net/browse/SOL-20).
In line 4 we include an image (thumbnail).  We absolutely *need* to include an ALT attribute here:
```<img src="<%= thumbnail %>" alt="">```
When this image is originally uploaded, is a description added?  the ALT attribute should include the description, if available, if not "No description available"