RFC: Add puma as the default smart-proxy server

Would this change require SCLing the smart proxy or are we able to switch to puma without making the packaging change? We already package puma as an RPM within the SCL so modifying it for system Ruby as well shouldn’t be too difficult if it can support Ruby 2.0. If this will require SCL, then we should discuss that and timeline to get both done.

BTW, I am all for this, I just jumped right into the logistics out of excitement :slight_smile: