def poweroff_vapp(vAppId)
      builder = Nokogiri::XML::Builder.new do |xml|
      xml.UndeployVAppParams(
        "xmlns" => "http://www.vmware.com/vcloud/v1.5") {
        xml.UndeployPowerAction 'powerOff'
      }
      end

      params = {
        'method' => :post,
        'command' => "/vApp/vapp-#{vAppId}/action/undeploy"
      }

      response, headers = send_request(params, builder.to_xml,
                      "application/vnd.vmware.vcloud.undeployVAppParams+xml")
      task_id = headers[:location].gsub(/.*\/task\//, "")
      task_id
    end
def poweroff_vapp(vAppId)
      builder = Nokogiri::XML::Builder.new do |xml|
      xml.UndeployVAppParams(
        "xmlns" => "http://www.vmware.com/vcloud/v1.5") {
        xml.UndeployPowerAction 'powerOff'
      }
      end

      params = {
        'method' => :post,
        'command' => "/vApp/vapp-#{vAppId}/action/undeploy"
      }

      response, headers = send_request(params, builder.to_xml,
                      "application/vnd.vmware.vcloud.undeployVAppParams+xml")
      task_id = headers[:location].gsub(/.*\/task\//, "")
      task_id
    end
Shutdown a given vapp