Content-derived resource IDs

[jcjones]

ietf-wg-ppm/draft-ietf-ppm-dap#781

Handle what wasn't already done for server-selected IDs. Audit all the HTTP Handlers.

Note that the spec also suggests aggregate-share ID == collection job ID.

[tgeoghegan]

The suggestion that aggregate share ID == collection job ID is being removed in ietf-wg-ppm/draft-ietf-ppm-dap#793 because we realized it was poorly written and probably impossible to implement. For Janus, I would go with random IDs, since we already do that, but then deriving it from the request is probably fine too.

[jcjones]

Thanks for the reminder!