update opentracing spancontext interface

Prepare release 0.5.0 (jaegertracing#169)

Signed-off-by: FR-MUREX-COM\mchaikhadouaihy <mehrez.douaihy@gmail.com>

Preparing for release 0.4.2 (jaegertracing#123)

Signed-off-by: Isaac Hier <isaachier@gmail.com>

Preparing for release 0.4.1 (jaegertracing#104)

* Preparing for release 0.4.1

Signed-off-by: Isaac Hier <isaachier@gmail.com>

* Update changelog

Signed-off-by: Isaac Hier <isaachier@gmail.com>

Fix release date (jaegertracing#98)

Signed-off-by: Isaac Hier <isaachier@gmail.com>

Preparing for release 0.3.0 (jaegertracing#85)

Signed-off-by: Isaac Hier <isaachier@gmail.com>

Add extra line to changelog (jaegertracing#42)

Signed-off-by: Isaac Hier <ihier@uber.com>

Preparing for release 0.1.0 (jaegertracing#22)

Signed-off-by: Isaac Hier <isaachier@gmail.com>

Preparing for release 0.0.8 (jaegertracing#16)