face: Implement WebSocket channel, face, and factory.

Change-Id: Ic4dbb1abdbbdbec028746ba14b11be8ab9cc1edb
Refs: #1468
diff --git a/core/face-uri.hpp b/core/face-uri.hpp
index 487f8f8..94474c7 100644
--- a/core/face-uri.hpp
+++ b/core/face-uri.hpp
@@ -79,6 +79,9 @@
   explicit
   FaceUri(const boost::asio::ip::udp::endpoint& endpoint);
 
+  /// construct tcp canonical FaceUri with customized scheme
+  FaceUri(const boost::asio::ip::tcp::endpoint& endpoint, const std::string& scheme);
+
 #ifdef HAVE_UNIX_SOCKETS
   /// construct unix canonical FaceUri
   explicit