Cross process task tracing - fixes 34

Fixes #34.
I tried pretty printing the output using `python examples/server.py 2>/dev/null | while read line; do echo $line | python -m json.tool; done` but python doesn't flush it's output when its connected to a pipe.

Perhaps it'd be nice to show how to run these examples. eg `python -u examples/server.py 2>/dev/null | while read line; do echo $line | python -m json.tool; done`