Migrate from google groups to discourse

As discussed we want to move google groups to discourse.

This seems to be the steps in general we must take:

- The box must be setup (@benoitc)
- Working groups chairs/volunteers need to be informed that we will be cutting over (heads up)
- We need to make sure we can login to the instance with wildapricot credentials
- We need to create each group
- On a weekend adjust all the aliases so that emails go to discourse instead of `@googlegroups`

As far as handling what's in google groups and whether to move those posts over to discourse: I am not sure. I suppose we can ask each WG whether they actually care about said posts. Or simply let the WG deal with that on their own.