New online forum for Labrigger

Here are the new Labrigger forums, running on Discourse.

Background: Justin Kiggins asked about having a Slack channel for Labrigger. The poll indicated majority support, so we agreed to set it up. Alexander Chamessian suggested using Discourse instead of Slack, we investigated and found it was cheaper and had better organization for this type of communication.

Thanks to Julia Lord for helping to set this up.