Add test based on the Jaeger spec (#645)
Add test based on the Jaeger spec (#645)

* Add test based on the spec
* Fix the other tests which appear flaky
* Clarify the randomness in these tests
* Add concrete example from Go for the trace id splitting
* Fix style
open-telemetry/opentelemetry-php,open-telemetry/opentelemetry-php,open-telemetry/opentelemetry-php