Make_unique function is added

The PR adds make_unique as it described in Working Draft of Standard for Programming Language C++ Document Number: N4296, Date: 2014-11-19, Revises: N4140.


It would be nice to see in the documentation a couple of words about what this function actually does (though smart people like us can figure out it from the \return declaration). Like here for example http://en.cppreference.com/w/cpp/memory/unique_ptr/make_unique