No feedback in downloads

When a download is started by clicking the "download button" no feedback is given.

Originally the suspect was ocs-manager but after manually testing sending an item download request it does returned the download progress feedback. More details about the test can be found in this issue

So, I decided to debug the opendesktop-app code. It happens that the download request is never sent from the app therefore no download progress feedback will be provided from the ocs-manager.

To solve this issue we must ensure that a download request is sent to the ocs-manager. This request must use the function ItemHandler::getItemByOcsUrl and in the data section the url must start with ocs://download.

I suppose that such url is provided by pling.com