Merge pull request #30 from rodgert/master

Make socket extension mechanism private detail
Merge pull request #31 from rodgert/master

resolve #5 Add socket specializations for router, dealer, etc.
Sockets specializations reimplemented as template + typedefs.

Current approach solves VS2013 inability to generate move ctor/move assign
and also reduces duplicated code.
Merge pull request #33 from oliora/master

Sockets specializations reimplemented as template + typedefs.
Pull detail::specialized_socket out of versioned namespace