Continuation of #246 (Github Pull Request)

Discord client IDs are numeric (e.g. 12345).
Passing them as integers however, causes the Discord bridge's YAML parser
to parse them as integers and its config schema validation will fail.

Fixes #240 (Github Issue)

This only gets triggered if:
- the Synapse role is used standalone and the default values are used
- the whole playbook is used, with `matrix_mxisd_enabled: false`

Continuation of #234 (Github Pull Request).

I had unintentionally updated the documentation for the feature,
saying the page is available at `https://matrix.DOMAIN/nginx_status`.

Looks like it wasn't the case, going against my expectations.

I'm correcting this with this patch.
The status page is being made available on both HTTP and HTTPS.
Serving over HTTP is likely necessary for services like
Longview
(https://www.linode.com/docs/platform/longview/longview-app-for-nginx/)

Also discussed previously in #213 (Github Pull Request).

shared-secret-auth and rest-auth logging is still at `INFO`
intentionally, as user login events seem more important to keep.
Those modules typically don't spam as much.

We recently had someone in the support room who set it to `false`
and the playbook ran without any issues.

This currently seems to yield the same result as 'none', but it's
better to avoid such behavior.

Refer to 524436ebef and #230 (Github Issue).

Fixes #230 (Github Issue).

Related to https://github.com/Half-Shot/matrix-appservice-discord/issues/510

It adds support for a new `DISABLE_SENDER_VERIFICATION` environment
variable that can be used to disable verification of sender addresses.

It doesn't matter for us, but we upgrade to keep up with latest.

Related to #223 (Github Pull Request)

Looks like these client ids are actually integers,
but unless we pass them as a string, the bridge would complain with
an error like:

    {"field":"data.auth.clientID","message":"is the wrong type","value":123456789012345678,"type":"string","schemaPath":["properties","auth","properties","clientID"]}

Explicitly-casting to a string should fix the problem.

The Discord bridge should probably be improved to handle both ints and
strings though.

Regression since 174a6fcd1b3, #204 (Github Pull Request),
which only affects new servers.

Old servers which had their passkey.pem file relocated were okay.

ef5e4ad061 intentionally makes us conform to
the logging format suggested by the official Docker image.

Reverting this part, because it's uglier.

This likely should be fixed upstream as well though.

Somewhat related to #213 (Github Pull Request).

We've been moving in the opposite direction for quite a long time.
All services should just leave logging to systemd's journald.

Fixes a regression introduced during the upgrade to
Synapse v1.1.0 (in 2b3865ceea).

Since Synapse v1.1.0 upgraded to Python 3.7
(https://github.com/matrix-org/synapse/pull/5546),
we need to use a different modules directory when mounting
password provider modules.

Fixes a problem introduced by da6edc9cba.

Related to #145 (Github Pull Request).

This is a new feature of Synapse v1.1.0.

Discussed in #145 (Github Pull Request).

Well, `config.yaml` has been playbook-managed for a long time.
It's now extended to match the default sample config of the Discord
bridge.

With this patch, we also make `registration.yaml` playbook-managed,
which leads us to consistency with all other bridges.

Along with that, we introduce `./config` and `./data` separation,
like we do for the other bridges.