[UNOMI-601] - Integration of timeStamp field to metadata class

[Saadmairaj]

Added a timestamp attribute which defines and stores the current time when the Metadata class is initialised.

This can be very useful as It gets challenging to sort and manage documents like segments, campaigns, lists, goals & rules as the timestamp field is missing. Adding an extra field timeStamp to metadata will give a timestamp field for all the documents other than profiles, sessions & events.

• [x] I hereby declare this contribution to be licenced under the Apache License Version 2.0, January 2004

[sergehuber]

Hello,

Thank you for your interesting contribution. Please note that we require integration tests for such contributions. Also, I've put a comment on the ticket (https://issues.apache.org/jira/browse/UNOMI-601) because I was thinking about these type of metadata more globally. Could you please check and look there to see how we want to move forward with this?

Best regards, Serge Huber.

[sergehuber]

Can we close this PR as there hasn't been any reply since June 25th ?