Comment 1 for bug 1496562

Attached branch has a fix. dns-search can be appended in two places:

- subnets
  - type static
    address 1.1.1.1
    dns-search:
       - path1
       - path2

or

- subnets
  - type static
    address 1.1.1.1
    dns-search: path1 path2

or

- nameserver
  address: 8.8.8.8
  search: path1 path2

or

- nameserver
  address: 8.8.8.8
  search:
    - path1
    - path2

curtin will inject

dns-search <paths> either under the specified interface (if configured under subnets)
or if using nameserver config, then it will appear underneath all iface lines.