Create a Q&A webapp to replace the etherpad

We plan to build a custom webapp for the Q&A to replace the etherpad. @pollo needs to scour the web to see if there isn't already a project we could reuse.

If not, @pollo has volunteered for grunt work and @stefanor to help with design. The Q&A program used by Audrey Tang at DC18 seems like a good model UI-wise (https://www.sli.do).