Admin Panel - Media Problems#142

I am using the admin panel to upload media as it detailed in the `uploading-files.md` docs. My schema looks like this: ```json "media": { "additionalProperties": false, "properties": { "additional_pic_01": { "format": "file", "links": [ { "rel": "Download File", "href": "/images/{{self}}", "download": true } ], "media": { "binaryEncoding": "base64" }, "type": "string" }, ``` In the admin panel the UI looks like this:  1. There is no way for me to clear the `additional_pic_01` or any of the media properties, i can only select a new image. I can clear it via the json dropdown but this is cumbersome 2. Thumbnail - it states `invalid data URI` because i am using a custom storage implementation. What would be nice, if, similar to how you can specify the `href` for `link`, this could be used to specify a custom thumbnail URI 3. The general layout is not very pleasing. This is exasberated by the lack of a thumbnail, but in particular the `Download File` link seems like it belongs to the the picture below