Improve Release Script
Improve Release Script

This change ensures that the created tag is signed.

alexander071/cf-java-client,cloudfoundry/cf-java-client,Orange-OpenSource/cf-java-client,cloudfoundry/cf-java-client,cloudfoundry/cf-java-client,alexander071/cf-java-client,Orange-OpenSource/cf-java-client,orange-cloudfoundry/cf-java-client,orange-cloudfoundry/cf-java-client