Implement Retention Policy for the JobRun Directory (migrated)

[michaelschnyder]

originally added by @michaelschnyder on Apr 5, 2015 on the old repo

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Jobbr Creates a working and temporaty directory where the actual job is running in (Working Directory). After completion, Jobbr collects all files stored in the working directory and transmits them to the jobbr-server.

The working directory an temp directory could be deleted after a given amount of time. This should not affect the jobbr-job artefacts repository.