[maven-release-plugin] prepare release gcloud-maven-plugin-0.9.57.v20150425
[maven-release-plugin] prepare release gcloud-maven-plugin-0.9.57.v20150425

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