This reverts commit 61e93744ec. Reverting because of: - https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/341 - https://github.com/matrix-org/matrix-appservice-slack/issues/347
61e93744ec
NeDB is deprecated, so we should transition away from it in the future. Still, most of the functionality should work on this new version.