Using variables for worker_processes and worker_connections

Using variables for worker_processes and worker_connections

Add defaults for matrix_nginx_proxy_proxy_synapse_worker_processes and matrix_nginx_proxy_proxy_synapse_worker_connections

Add default matrix_riot_web_worker_processes and matrix_riot_web_worker_connections

Certain people organize their inventory in a different way
and we'd like to accommodate them.

Related to #542 (Github Issue).

Fixes #542 (Github Issues).

Fixes #539 (Github Issue).

Fixes #523 (Github Issue).

Besides /_synapse/admin, there are other things like
/_synapse/oidc, etc.

We should just proxy everything.

Fixes #534 (Github Issue).

There's no change in the source code. Just a release bump for packaing
reasons. It doesn't matter much for us here, but let's be on the latest
tag anyway.

Postgres setup like
matrix_mautrix_telegram_configuration_extension_yaml: |
  appservice:
    database: "postgres://XXX:XXX@matrix-postgres:5432/mxtg"

 will fail without the right Dockernetwork

`/etc/nginx/conf.d/default.conf` was previously causing
some issues when used with our `--user`.

It's not the case anymore, so we can remove it.

Fixes #369 (Github Issue).

because the tty port will change

Depending on the distro, common commands like sleep and chown may either
be located in /bin or /usr/bin.

Systemd added path lookup to ExecStart in v239, allowing only the
command name to be put in unit files and not the full path as
historically required. At least Ubuntu 18.04 LTS is however still on
v237 so we should maintain portability for a while longer.

the current version fails the import, because the volume for the media is missing. It still fails if you have the optional shared secret password provider is enabled, so that might need another mount. Commenting out the password provider in the hoimeserver.yaml during the run works as well.