Test for seneca-zipkin-tracer

To run the test, ensure you have zipkin listen on localhost, then run

npm install

then call one after another:

node service1
node service2
node service3

After all services listen, run

node client

On each service i log the request-params to the console and there are all parentId's from tracer empty. In Zipkin you will see 3 individual spans, but i expected one with 3 sub-spans.