PyS2OPC DataValue Source and Server timestamps set to unix epoch
Description
When writing values, OPC-UA servers store the unix epoch (01/01/1970) as the source timestamp.
Analysis
When the C DataValue is built, the value 0 is converted by float_to_datetime to the windows date 01/01/1970. In this case, the timestamps must stay 0, which indicates to the S2OPC toolkit that it should not be encoded.