tools: improve user experience by choosing best certificate
automatically and print final response in a pretty way

ndns-update
 - pick the best certificate to sign the Update automatically
 - support multiple token for content option

ndns-dig
 - enhance output option
 - change behavior of iterative query controller when NS query is NACKed

logger
 - set default logger output to std::cerr

Change-Id: Ib06981c224ccad2a122a4505c84a60977184a55b
mgmt: management tools

refs #2034

Change-Id: I43ff11e0aa7e67f6207e75f139b7417779590efc
tools: add ndns-demo

Change-Id: I250d7bf8a02ffec8aee3226bbf830bc3e9bbfa3f
tools: add NdnsShot

Change-Id: Ia34e0228e6e9164239f3412e5c419f965e35daec
add root cert and shell script to simplify testing

Change-Id: I15171cf06f3b9b3e55909109a3bf99d2d6176a35