This enables more advanced customisation by allowing for
administrators to fully replace the footer of the login theme.
We try to take into account maintainability, at the same time mention
that it is the administrators' responsibility to keep their
customisations compatible with newer versions of DD.
This can be used by setting up HAPROXY_CONF in dd.conf, which will
determine which config file will be used.
We also add haproxy.proxy-protocol.conf which is cleaner than
haproxy.conf and allows the PROXY protocol on certain ports.
With this setup it is possible to e.g. run DD without a public IPv4
address by proxying it from an edge server.
Evilham