Upgrade riot-web to v1.0.3

Add support for custom MXISD templates

Related to #105 (Github Pull Request).

Related to #105 (Github Pull Request).

Related to #105 (Github Pull Request).

It didn't mention `matrix_appservice_discord_client_id` and
`matrix_appservice_discord_bot_token`, which makes it hard for
beginners.

Related to #105 (Github Pull Request).

Add Support for matrix-appservice-discord

Generates the link required to add the Bridge to a Discord server.

Bridge is setup to work on the matrix side with this, but the discord invite link is not automatically generated.

Fixes #69 (Github Issue)

fixed a small path typo in playbook telemetry docs

The Server spec says that redirects should be followed for
`/.well-known/matrix/server`. So we follow them.

The Client-Server specs doesn't mention redirects, so we don't
follow redirects there.

Using `docker_container` with a `cap_drop` argument requires
Ansible >=2.7.

We want to support older versions too (2.4), so we either need to
stop invoking it with `cap_drop` (insecure), or just stop using
the module altogether.

Since it was suffering from other bugs too (not deleting containers
on failure), we've decided to remove `docker_container` usage completely.

Some resources shouldn't be cached right now,
as per https://github.com/vector-im/riot-web/pull/8702

(note all of the suggestions from that pull request were applied,
because some of them do not seem relevant - no such files)

Fixes #98 (Github Issue)

It's not important for us, as it only contains
some ACME-related fix.

`matrix_synapse_no_tls` is now implicit, so we've gotten rid of it.

The `homeserver.yaml.j2` template has been synchronized with the
configuration generated by Synapse v0.99.1 (some new options
are present, etc.)

This reverts commit 536c85619f.

Looks like binding metrics on IPv6 (`::`) fails with an error:

socket.gaierror: [Errno -2] Name does not resolve

We had something like that on the Server Delegation how-to page,
but it's better if we have it on the SSL certificates page.

Relocated there and improved linking.

Fixes #94 (Github Issue)