DEVEN-201 New Feature network-specific appenddomain and support networks
without DHCP management
* [appenddomains] section carries per-network appenddomain data
* Started to refactor tests into single files per function
* LML::Config::get_array to return array, get always returns string
* LML::VMpolicy::validate_vm_dns_name active only if VM connected to
  [dhcp] managed_networks
* DNS Domain is now part of VM data, handled in LML::VM with
  set_dns_domain and retrieved with dns_domain
  
NOTE: dhcp config file will contain data for all hosts, regardless if
they are managed by DHCP. ISC dhcpd does not care about extra data.
Merge branch 'master' of ssh://git@github.com/ImmobilienScout24/lab-manager-light.git