Call for WineConf presentations

[Aric Stewart]

Ok lots of discussion which is great.

I think I caught Zeb actually wanting to schedule a slot.  So I can do that.

Right at this moment I have:
 * Keynote - Alexandre Julliard
 * CodeWeavers Company Update - Jeremy White
 * State and future of Wine-Staging - Zebediah Figura
 * Winetest infrastructure discussion - Jeremy White
 * WineConf 2019 discussion

And 10 open slots.

-aric