Specify a SHA-1 or SHA-2 cert depending on client abilities

This isn't currently possible with nginx (though it is with apache). However, it seems that companies like CloudFlare have already implemented their own internal modifications of nginx to be able to do so and will hopefully be open sourcing their work (https://news.ycombinator.com/item?id=8276770), so I'm hoping/expecting nginx will have this ability in a year from now when the need becomes more pressing as we approach 2016.

In the meantime, i just bought a 1-yr cert expiring in late 2015 so i don't get hit by Chrome's warnings until a hopefully a feature like this comes out.