switch to using the upstream nixos mattermost module

this does start up correctly, creating its state directory and so on.

it isn't yet world-visible, because we don't have the SSO set up yet.
that's likely to make testing it difficult, which is unfortunate but
necessary, since there's no way it's secure.

Change-Id: I9f40c21c2d41f7e037299cc51a26fdee4d53d3af

0 files changed, 0 insertions, 0 deletions