V0.6.6: Metrics not pushed to back-end - EmptyTraceContext present while closing the trace with token

[gmalouf]

Originally posted at kamon-io/Kamon#465, but probably should have been here. Starting with 3d31d6e - metric recording is broken as the units tests show.

Easy way to reproduce:

get { path("status") { traceName("Status") { complete("A-OK") } } }