Commit-Status: use most recent status

Instead of the oldest.

Github api returns statuses in oldest-first order, see:
https://api.github.com/repos/danielbeardsley/cimpler/statuses/3f0625b46ecb0c1d6789546f7c2f3d5b91a8ca5e

4 statuses, the last one is the the most recent.

Not sure how this is working for anyone as most commits have at least
two statuses (started, finished)