Go agent v2.4

2.4.0 Notes

• Introduced Transaction.Application method which returns the Application that started the Transaction. This method is useful since it may prevent having to pass the Application to code that already has access to the Transaction. Example use:

txn.Application().RecordCustomEvent("customerOrder", map[string]interface{}{
    "numItems":   2,
    "totalPrice": 13.75,
})

• The Transaction.AddAttribute method no longer accepts nil values since our backend ignores them.