image (string): This param allows you to customize the podcast feed image.
This will return a podcast feed with the 60 most recent media items related to category 1 with a custom image.
The API will check to see if the file exists at /assets/img/filename.png. If the file exists, the custom image will be included, if it does not, the default image will be used. REMEMBER: do not upload these files directly to the server, you must commit them to the repo.