mod_http_oauth2: Reuse JWT issuance time as substitute for auth time
Makes the token shorter. Since iat and auth_time are generated at about
the same time they would only differ by a few microseconds anyway.
This module helps reduces power usage of inactive mobile clients while
another client is actively used. E.g. in the case of chatting on a
desktop computer, instantly pushing messages to a phone in someones
pocket is not the best use of radio time.
Works with [mod_csi_simple][doc:modules:mod_csi_simple] which is
included with Prosody since 0.11