Refactor some parts of the Architecture:

* JSON visitor are located in the format namespace
  * Visitor are *real* visitor
  * Visitable class has been renamed to Object
  * Due to a bug in Visual Studio 2015, we move to VS2017

api/python/MachO/objects/pyRPathCommand.cpp

@@ -18,7 +18,7 @@
 #include <string>
 #include <sstream>
 
-#include "LIEF/visitors/Hash.hpp"
+#include "LIEF/MachO/hash.hpp"
 #include "LIEF/MachO/RPathCommand.hpp"
 
 #include "pyMachO.hpp"
@@ -45,7 +45,7 @@ void init_MachO_RPathCommand_class(py::module& m) {
     .def("__ne__", &RPathCommand::operator!=)
     .def("__hash__",
         [] (const RPathCommand& rpath_command) {
-          return LIEF::Hash::hash(rpath_command);
+          return Hash::hash(rpath_command);
         })