User and invitation management

I wanted to let you know that big improvements are coming, but first up is the ability to uninvite team members.

A small improvement, but it's the first of a raft in the pipeline. A new/improved retrospective meeting interface, additional retrospective formats, and soon integrations with your project management tooling.

For those of you using RemoteRetro, 🙏🏻 and if you have any feedback, suggestions or complaints, I'm all 👂🏻. Please email me at mark@remoteretro.io