[maven-release-plugin] prepare release gcloud-maven-plugin-0.9.56.v20150415a
[maven-release-plugin] prepare release gcloud-maven-plugin-0.9.56.v20150415a

GoogleCloudPlatform/gcloud-maven-plugin,GoogleCloudPlatform/gcloud-maven-plugin,ludoch/gcloud-maven-plugin,GoogleCloudPlatform/gcloud-maven-plugin