* fix comments and add jaeger tests
* add more jaeger tests
* remove TODOs and add more jaeger tests
* remove TODOs and add more jaeger tests
* fix jaeger tests
* add jaeger agent tests
* fix merge conflicts and fix test
* fix test name
* shrink the value type
went down from 40 bytes to 24
* add missing license blurb
* stringify value type
* print string value types in stdout exporter
* make Value function take a pointer receiver
* api(trace): change trace id to byte array.
* fix lint errors
* add helper to create trace id from hex and improve stdout exporter.
* remove comma.
* fix lint
* change TraceIDFromHex to be compliant with w3 trace-context
* revert remove of hex16 regex because its used to parse SpanID
* lint
* fix typo
* setup sdk exporter package
* use sdk exporter package in sdk trace
* use sdk exporter package in all exporters
* empty the exporters list before testing Load
* move SpanData to the exporter package
* use the SpanProcessor registration, don't register exporters
* rename exporter structs to avoid stutter
* rename Syncer and Batcher to SpanSyncer and SpanBatcher
So it's explicit they are for spans, and we reduce the risk of name
conflict
* remove not moot todo
* rename sdk exporter to export
* only execute the SpanData if it is sampled
This is to shrink the PR #100.
The only place where the registry.Variable type was used was metrics,
so just inline that type into its only user. The use of the
registry.Variable type in core.Key was limited to the Name field.
The stats package also used the registry.Variable type, but seems that
also only the Name field was used and the package is going to be
dropped anyway.