code: private static String getDeploymentClassNameFromXml(ArquillianDescriptor descriptor) {
          ExtensionDef extension = descriptor.extension("suite");
          if (extension != null) {
              return extension.getExtensionProperties().get("deploymentClass");
          }
          return null;
      }
docs: Returns name of class witch should be used as global deployment.
  Extension name used: suite
  Key: deploymentClass
  
  @param descriptor ArquillianDescriptor
  @return full class name from arquillian.xml