Decide on order for codebase `all_contributors` aggregate

[cpritcha]

Currently there is an ordering on release contributors but none on the aggregation of all release contributors. Need to decide on a consistent ordering given release contributor orderings.

[alee]

This isn't very high priority but when you get around to it we could order by release first, then merge in the later contributors from subsequent releases. As an example:

Release 1.0.0: (Calvin, Christy, Allen, Seema, Michael) Release 1.1.0: (Calvin, Marco, Andres, Joffa, Michael) would result in: (Calvin, Christy, Allen, Seema, Michael, Marco, Andres, Joffa).