[WIP] Contributor plots

[bourque]

This PR introduces contributors-plots.py, which creates plots showing the number of contributors to astropy-affiliated packages over time. This work was done as part of the .astronomy 2018 hack day. The original idea for this is attributed to @eteq !

Some lingering questions/issues include:

1. Right now this just uses default matplotlib style plots. It would perhaps be better to do this in bokeh or advanced matplotlib instead.
2. Currently this isn't smart enough to exclude cases where someone has changed their GitHub username. In those cases, if someone is operating under more than one username, they would be counted more than once in the resulting plots.
3. Eventually, it would be nice to expand this out to the whole "astropy python ecosystem" as @eteq suggests.
4. This code just saves the plots to a locally directory called contribution-plots, but perhaps there is a better place to store this data.
5. This is not at all tested or contains any error handling for corner cases (e.g. user does not have supplied their GitHub auth token).

[bsipocz]

@bourque - Why the plot for astropy only goes up to ~100? should be more like ~240+

[bourque]

@bsipocz Thanks for catching that. Let me look into it, and tag this as a WIP. Like I said, this effort was part of a hack day so there are likely some shortcomings.

[bsipocz]

and it's a super useful hack :)

[bourque]

I'm not quite sure what is going on here. Though the main page of the astropy repo claims 266 contributors, when I visit the contributors page it only lists 100, which is what is also returned from the request to https://api.github.com/repos/astropy/astropy/stats/contributors. The GitHub REST API warns that the statistics do not include merge commits, but i'm not sure that would account for the 166 people.

I thought that perhaps the REST API was returning the results in pages, but when I try https://api.github.com/repos/astropy/astropy/stats/contributors?page=2, it doesn't seem to alter the returned results.

[bsipocz]

The contributors page is always limited to show the top 100 people. For the webpage and all other stats we actually always used the full git log instead, as not all the contributors are on github any more, or their e-mail address they made the contributions with might not recognized by github. Maybe it's also possible to do with the API, but I don't know how.

[pllim]

Thanks, but I think there are better places out there now for such contributions.

https://devstats.scientific-python.org/