daemon: add NameServer

Change-Id: I64b82a0e9351bcc15691279470c807399480a474
clients: add dig

Change-Id: I78822e9d68b36973362f0790f3c2f6e676cc6b94
add NdnsUpdate

Change-Id: Ia34e0228e6e9164239f3412e5c419f965e35daec