read-only cache support

[jpark800]

Current behavior:
Tuples objects are transient. i.e. It goes away when rule engine shuts down.

Expected behavior:
Selected tuple data to be available via cache regardless of a rule engine instance's lifecycle.

What is the motivation / use case for changing the behavior?
Long lasting factual data such as employee record would need to be more persistent compared to event data. Tuple object management should support such cases more natively.