In case a link relation's target exposes a profile link (via HTTP HEAD and "Link" response header), we now try to obtain a JSON schema from the target resource and use a custom view based on the JSON Editor library fro non-GET requests.
This creates a customized, user friendly pop-up dialog for data entry with a nice polished look. If there is no profile link, we use a fallback editor for raw JSON input.
Original pull request: #191.