Release v1.29.0 (googleapis#258)

Release google-oauth-java-client v1.28.0 (googleapis#244)

* Release v1.28.0

* Update maven-surefire-plugin

* Fix Kokoro release/drop configurations

Release google-oauth-java-client v1.27.0 (googleapis#235)

* Release v1.27.0

* bom needs developers section and release profile/configs

Release v1.26.0 (googleapis#227)

* Release v1.26.0

* Fix release snapshot version in samples

* Fix versions in the assembly package

* Actually enable the sonatype staging plugin

* Fix deploy order

Add plugin configuration to maven-release-plugin

Add plugin configuration to maven-release-plugin

Add plugin configuration to maven-release-plugin

Add plugin configuration to maven-release-plugin

Add plugin configuration to maven-release-plugin

Merge pull request googleapis#106 from google/release-1.20.0

Release 1.20.0