re-organize files and remove DbMgr

Change-Id: I6667dad558994f1ebcdfb54ab0ec0ed61e2cccb6
add response

Change-Id: Ia906b23b52f29483aacb30dae989db1b1e98a85d
add query

Change-Id: I59da2d9894ad35de56a11a9f063a19773d4cecad
add DbMgr again & testing data

the fake Response is not signed yet

Change-Id: I3e2153fe1d7bf68a9880b8ff533d9fe27d1e15ba
add NameServer

Change-Id: I64b82a0e9351bcc15691279470c807399480a474
add dig

Change-Id: I78822e9d68b36973362f0790f3c2f6e676cc6b94