Regression since #362 (Github Pull Request).

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

Synapse v1.9.0 changed some things which made the REST Auth Password
Provider break.

The ma1uta/matrix-synapse-rest-password-provider implements some
workarounds for now and will likely deliver a proper fix in the future.

Not much has changed between the 2 projects, so this should be a
painless transition.

This change allows us to work with both our existing Docker image
(`tedomum/matrix-appservice-irc:latest`) and with the
official Docker image (`matrixdotorg/matrix-appservice-irc`).

The actual change to the official Docker image requires more testing
and will be done separately.

Related to #355.

Regression introduced in 53186ffa1c

NeDB is deprecated, so we should transition away from it in the future.
Still, most of the functionality should work on this new version.

Related to #330 (Github Issue).

Fixes #330 (Github Issue).

This allows for users to bridge already existing matrix rooms to discord

https://github.com/matrix-org/matrix-doc/pull/1957

Yay Riot iOS now supports integration manager discovery!

Can you double check that the way I have this set only exposes it locally? It is important that the manhole is not available to the outside world since it is quite powerful and the password is hard coded.