Preparing release 1.21.0 (jaegertracing#2630)

* updated changelog

Signed-off-by: Joe Elliott <number101010@gmail.com>

* Added ui changelog

Signed-off-by: Joe Elliott <number101010@gmail.com>

* Fixed UI changelog to point to 1.12.0

Signed-off-by: Joe Elliott <number101010@gmail.com>

* Updated jaeger-ui to v1.12.0

Signed-off-by: Joe Elliott <number101010@gmail.com>

* Resolving concerns

Signed-off-by: Joe Elliott <number101010@gmail.com>

Release v1.20.0

Prepare release 1.19.1 (jaegertracing#2421)

* Prepare release 1.19.1

Signed-off-by: Yuri Shkuro <github@ysh.us>

* fix version

Signed-off-by: Yuri Shkuro <github@ysh.us>

Prepare release 1.18.1 (jaegertracing#2296)

Signed-off-by: Pavol Loffay <ploffay@redhat.com>

Preparing release v1.18.0 (jaegertracing#2244)

Signed-off-by: Pavol Loffay <ploffay@redhat.com>

Bump UI to 1.8

Signed-off-by: Pavol Loffay <ploffay@redhat.com>

Remove empty "breaking changes" section

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

Preparing release 1.16.0 (jaegertracing#1980)

* Preparing release 1.16.0

Signed-off-by: Pavol Loffay <ploffay@redhat.com>

* Add 1937

Signed-off-by: Pavol Loffay <ploffay@redhat.com>

* Remove

Signed-off-by: Pavol Loffay <ploffay@redhat.com>