Error handler failure reason as context data

[gschueler]

Make context data available to error handlers that includes the reason for failure of the step.

context data:

• result.reason
• result.message
• result.resultCode (executions)

Examples of "result.reason" values:

• NonZeroResultCode (command execution)
• HostNotFound (remote node can't be contacted)
• ConnectionTimeout
• etc

[gschueler]

job reference arguments do not include expanded reason context data.

e.g. job reference as error handler, args "-message ${result.reason}", the result.reason is not expanded when the error handler is executed.