management: Adding nfd::FaceEventNotification data structure

Change-Id: I5b5b8b0f86a5ccd4ed82561aaf87118400a0ba33
Refs: #1244
face: making Face::shutdown call asynchronous

After Face::processInterestFilters changed to dispatch all callbacks
that match the configured filters, calling shutdown() from inside the
callback caused segfault (unexpected invalidation of the iterator).

Change-Id: Ia0a3048ce3574d354071e091c2d9400ad9a263b4
Refs: #1366
management: Adding nfd::FaceStatus data structure

Change-Id: I45585a17a4163931c38ece5621d12489aa6a3b73
Refs: #1328
encoding: Fixing bug in one of the Block constructors

Change-Id: I8ed98c8b9947e876e0f95864a7d83422b26e01fb