By default, `--tags=self-check` no longer validates certificates
when `matrix_ssl_retrieval_method` is set to `self-signed`.
Besides this default, people can also enable/disable validation using the
individual role variables manually.
Fixes#124 (Github Issue)
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.
