Prepare to active documentation view

tracim/__init__.py

     default_controllers.bind(configurator)
     session_api = SessionController()
     session_api.bind(configurator)
+    # hapic.add_documentation_view(
+    #     '/api/v2/doc',
+    #     'Tracim v2 API',
+    #     'API of Tracim v2',
+    # )
     return configurator.make_wsgi_app()