This allows us to compile NFD in C++11 mode, making use of std::shared_ptr,
std::function, std::bind, etc. rather than their boost equivalents
(provided that ndn-cpp-dev is also compiled in C++11 mode). This is an
experimental feature and may not work properly.
Change-Id: I310529f78e1e428a8530b087983130d1ef3a9d88