Added missing subsonic configuration block in deployment vhost files (#249)

Missing subsonic configuration bloc in vhost files
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Because of a missing bloc in the sample Nginx and Apache configurations,
instances that were deployed after the 0.13 release are likely to be unable
to answer to Subsonic clients (the missing bits were properly documented
in the changelog).

Ensure you have the following snippets in your Nginx or Apache configuration
if you plan to use the Subsonic API.

Nginx::

    location /rest/ {
        include /etc/nginx/funkwhale_proxy.conf;
        proxy_pass   http://funkwhale-api/api/subsonic/rest/;
    }

Apache2::

    <Location "/rest">
        ProxyPass ${funkwhale-api}/api/subsonic/rest
        ProxyPassReverse ${funkwhale-api}/api/subsonic/rest
     </Location>