overrides timestamps coming from frontend agents

[jalvz]

fixes #723

[roncohen]

nice @jalvz. Seems like timestamp should be optional if we're not going to use it. WDYT? We could make the logic that if the timestamp is missing in the payload, APM Server will add it. And then we change the frontend agent to make sure it's not included in the payload. cc @jahtalab

[graphaelli]

With all of the queueing we're doing I'm concerned that grabbing the timestamp at transform time will be late enough to be significant - what do you think?

Two options we could consider:

• extend ProcessorFactory to accept a context object that we stick a time.Now value in
• jam a ReceiveTime into config.Config

[jalvz]

We could make the logic that if the timestamp is missing in the payload, APM Server will add it

sure. that is basically re-do this with an schema change, so closing this.