/collector/track should return an array of Statement IDs in case we want to reference nested statements within other statements (supported by xAPI specification)

[RotaruDan]

The returned array of Statement IDs should be ordered the same way the statements have been sent to the /collector/track request.

NOTE: This could be an optional feature activated with a flag sent within the body of the request (example given) since returning the array can increase the network load and referencing nested Statements is not a priority use-case.