PORTVERSION when there is no upstream version number

[Manuel Wiesinger]

Hi,

what is the best practice for setting PORTVERSION, when the upstream 
port has no version number? Is it fine to go with the date like 20141021?

I'm trying to port postscreen-stats, which is just a collection of small 
scripts without any version numbering.
See: https://github.com/jvehent/Postscreen-Stats

Regards,
Manuel