docker: images optimisation: - reduced the number of layers by grouping many instructions - moved stuff which don't change a lot at the beginning, and hg/apt at the end - scripts are not now in scripts/ subdirectories - prosody.cfg.lua is added using ADD instead of getting it online - .hg/dirstate is copied in base (backend) and libervia, so mercurial revision is known - removed lot of useless WORKDIR instruction, they are replaced by "cd" inside RUN instructions - cleaning (apt-clean, rm) is done on the same instruction as the one than generate the data, to avoid useless data in layers

$ORIGIN 0.0.127.in-addr.arpa.
$TTL 1D
@     IN SOA  <hostname>.<domain>. <hostname>.<domain>. (
              <date>     ; serial
              28800      ; refresh (8 hours)
              14400      ; retry (4 hours)
              2419200    ; expire (4 weeks)
              86400      ; minimum (1 day)
              )

              NS      <hostname>.<domain>.
1             PTR     <hostname>.<domain>.