Identify output channel in JobScheduler logs

Starting Situation

• When a shell script is executed within a job and when this script writes messages to the standard output and error channels ("stdout", "stderr") then
  • the JobScheduler writes these messages to the task's log with severity "info", e.g.

    2015-03-18 07:57:38.991+0100 [info]   This message goes to stdout
    2015-03-18 07:57:38.993+0100 [info]   This message goes to stderr
    

  • A user cannot decide from the log if output has been written to stdout or to stderr.

Desired Behavior

• Logging
  • Messages received via the standard output and error channel can be identified from the log, e.g.

    2015-03-18 07:57:38.991+0100 [info] [stdout]  This message goes to stdout
    

    2015-03-18 07:57:38.993+0100 [info] [stderr]  This message goes to stderr
    

    Log messages to stderr are painted in red when displayed in a browser.

• Handling of errors
  • This feature does not affect the handling of errors.
  • For error handling in case of output to stderr see JS-1329 that implies precedence of log output formatting over what is stated in this isssue.