Get DOI from zenodo

[dpshelio]

zenodo offers DOI numbering for code directly from the release in github. It even makes a nice and beautiful badge :)

I think this should be done once we got the paper done with the final release we are writing about.

I'm not sure what's the difference between zenodo or figshare... We could do either I assume. Zenodo is the product of a EU project and it has the data stored at the CERN facilities.

[dpshelio]

This is easy, once we have the final version of sunpy we want to release with the paper I have just to click one button.