PutMetricDataNamespace MetricData.member.1.Value 0

Put metric value 0 is normal case. If not send 0, AWS SNS api return error message:
"Type: Sender, Code: InvalidParameterCombination, Message: At least one of the parameters MetricData.member.1.Value and MetricData.member.1.StatisticValues must be specified."
Merge pull request #301 from gronpipmaster/patch-1

PutMetricDataNamespace MetricData.member.1.Value 0