Inconsistent use of hyphens in the uuid

[Pingviinituutti]

Hi!

In the BaseVoltage.rdf definitions, it seems some uuids have hyphens in them while some don't, for example:

http://energy.referencedata.eu/BaseVoltage/7891a026ba2c42098556665efd13ba94

and

http://energy.referencedata.eu/BaseVoltage/b0966c86-9e5e-11e5-a575-c01885dc2c80

Would it make sense to update the reference data to use either the format with hyphens or the one without? I can make a pull request if relevant.

All the best,
Henrik