Authorized download link

[jennydaman]

To facilitate the downloading of files using a web browser client, it is necessary to implement one-time use download links. For example, let's say we have a file /api/v1/files/1/very_big.dat which belongs to a private feed. It can be downloaded by making an HTTP request using the Authorization header. However, for a web browser to download the file, it cannot send custom HTTP headers.

We should provide an API, something like POST /api/v1/files/1/download/ which will return a one-time download link, e.g. /api/v1/files/1/very_big.dat?token=abcdefg. This download URI should allow file download without a HTTP Authorization header.