Add a DOI using Zenodo

[ScottWales]

Should we set up zenodo at the start, or wait until we have some functionality in the library?

I've added coecms-util to my zenodo account, it looks like all you need to do is create a new release in Github, then zenodo gives you a DOI

[paolap]

I would rather wait, we don't have anything in here yet, but more importantly, we should first decide how to handle the software publishing workflow before starting a zenodo repository