Open requested to merge helmo/ispconfig3:patch-bind-zonefiles-prefix into develop
This continues on !1375 (merged) (and includes those commits to avoid merge conflicts)
These functions now switch on a check for gentoo, but as a Debian user I like the value it gets in gentoo. A separate folder for all master zone files makes more sense then adding 'pri.' as prefix to all these files.
I've set the default to be be the same for non-gentoo systems. How can we initialize these config options correctly with an update on gentoo systems?
PS: An alternative might be to start using this config option inside the zone_file_prefix() function and leave the value fixed for Gentoo users.