Add newrelic example

[erabug]

This example demonstrates how to instrument the client and server with the New Relic Java agent API.

It's a bit contrived: The agent "magically" instruments much of this example, so I have to disable the agent's automatic mode to demonstrate the API. Also, the propagation API is a prototype and is not publicly available.

Regardless, I think it still illustrates how our API instruments the New Relic concepts of a transaction and its segments. This is an example of the spans produced from the path B handler call:

[AloisReitbauer]

Erica,

we had the same issue. Usually this example would work out of the box. It will be interesting to see how trace APIs and automatic approaches can co-exist