Clones expiration time

[frankiejol]

Set all the clones from a base an expiration time. When this period of time has passed, all the clones will be automatically removed. An use case could be machines in an education center that have to be cleared at the end of semester.

This configuration settings could be:

• a period of time , ie : 2 months
• a certain date in the future, ie : 2025-12-31. When this time is near, a flag should be raised in the admin tools with a warning. Also, when it has passed another flag must warn this settings must be updated