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/ELF/objects/pyRelocation.cpp

@@ -15,7 +15,7 @@
  */
 #include "pyELF.hpp"
 
-#include "LIEF/visitors/Hash.hpp"
+#include "LIEF/ELF/hash.hpp"
 #include "LIEF/ELF/Relocation.hpp"
 
 #include <string>
@@ -74,7 +74,7 @@ void init_ELF_Relocation_class(py::module& m) {
     .def("__ne__", &Relocation::operator!=)
     .def("__hash__",
         [] (const Relocation& relocation) {
-          return LIEF::Hash::hash(relocation);
+          return Hash::hash(relocation);
         })
 
     .def("__str__",