GRAS-1366: Default image was added.
Merge branch 'joust' into features/GRAS-1366-Non-image-thumbnails-show-up-broken-in-the-file-browser
GRAS-1366: unsupported image format was removed
Merge branch 'joust' into features/GRAS-1366-Non-image-thumbnails-show-up-broken-in-the-file-browser
Merge branch 'features/GRAS-1366-Non-image-thumbnails-show-up-broken-in-the-file-browser' into joust