Tagging 4.0.0

Preparing release 4.0.0

Tagging 3.13.0

Tagging 3.12.0

Tagging 3.11.0

Tagging 3.10.0

Preparing release 3.10.0 (jaegertracing#173)

Signed-off-by: Won Jun Jang <wjang@uber.com>

Tagging 3.9.0

Preparing release 3.9.0 (jaegertracing#162)

* Preparing release 3.9.0

Signed-off-by: Won Jun Jang <wjang@uber.com>

* Add missing items

Signed-off-by: Yuri Shkuro <ys@uber.com>

Tagging 3.8.0