* install releasetool from github (#2842)
* install releasetool from github (#2842)


dazuma/google-cloud-ruby,quartzmo/google-cloud-ruby,googleapis/google-cloud-ruby,googleapis/google-cloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,dazuma/google-cloud-ruby,googleapis/google-cloud-ruby,googleapis/google-cloud-ruby,blowmage/gcloud-ruby,googleapis/google-cloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,quartzmo/google-cloud-ruby,googleapis/google-cloud-ruby,dazuma/google-cloud-ruby,dazuma/google-cloud-ruby,dazuma/google-cloud-ruby,dazuma/google-cloud-ruby