puavo-users: puavo-rest-bootserver breaks and replaces earlier puavo-rest-nginx
puavo-users: do not build-depend on build-essential

Build-dependencies on "build-essential" binary packages can be
omitted [1].

[1]: http://www.debian.org/doc/debian-policy/ch-relationships.html#s-sourcebinarydeps
puavo-users: 0.4.32-0+opinsys4
puavo-ltsp: bootserver suggest ntp instead of depend on it