Fix typo

Author: vidartf

{{cookiecutter.github_project_name}}/{{cookiecutter.python_package_name}}/example.py

@@ -21,8 +21,8 @@ class ExampleWidget(DOMWidget):
     _model_name = 'ExampleModel'
     _model_module = Unicode(module_name).tag(sync=True)
     _model_module_version = Unicode(module_version).tag(sync=True)
-    _model_name = 'ExampleView'
+    _view_name = 'ExampleView'
     _view_module = Unicode(module_name).tag(sync=True)
     _view_module_version = Unicode(module_version).tag(sync=True)
 
-    value = Unicode('Hello World')
+    value = Unicode('Hello World')