Local DNS

[Plopmenz]

Run a local DNS server to declarative configure the DNS entries to all apps running on this Xnode.
Allows for dns-01 challenge verification for the xnode-manager ACME.

Issues:

• Every Xnode gets assigned a domain (zone), transferring apps to other Xnodes can ideally be done without making any changes to the DNS of the provider. How to keep application domain records independent of Xnode (DNS zone)?