with the latest commit is working but sincerely I think something could be broken: User.user.invitations.guilds items doesn't have a `_id` property but a `id`, I sincerely don't know why but in the party/guild/group controllers there are a lot of references to `_id` and some to `id`, it shouldn't always be `_id`?

Then if you invite someone to a guild there should be something like "pending invite for xxx" but nothing is shown even though the populate after the invitation is sent should add the user to members or not?

I also added some fixes that aren't related to this pull, small ones.