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
logger: Fixing the bug with redirecting of log output to the standard error

Change-Id: I4f84548643a4ea3b0b1ef8f341e39d01e90eb55b
tests: Improving ManagementTool test suite and fixing discovered bugs

Change-Id: I1c7e51cf105544325657825474f9ee85d61396ed
Refs: #2226