[TAP] Fix bug with the UPLOAD parameter: on any job parameter modification (with a 2nd http request), the UPLOAD parameter was deleted
[UWS] Stringify an array parameter (e.g. UPLOAD which is an array of DALIUpload objects in TAP)
[UWS,TAP] Review some log messages (in the log file but also in the error summary of a job) ; particularly stack traces are added into the error summary, but are displayed just once in the logs.