[demo] Add docker-compose for collector and jaeger

[breedx-splk]

When running the demo app, the telemetry data should have somewhere to go.

We can use docker-compose and create a docker-compose.yml that spins up a configured collector and jaeger. We might not need the collector, and could just ingest directly to jaeger for the demo purposes....but I think it might be nice to have the collector as a place to wire up additional logging and/or other pipeline components.

When this issue is done, it should be easy to start the demo app and see some telemetry in the collector logs and in jaeger.

The README should be updated with the simple/clear instructions on how to start the "backend" and launch the demo via emulator.

[breedx-splk]

I've started on this work.