Fix issue where name was doubled up when using EditorFor

Hi John,

I figured out a simpler way to fix this issue instead of futzing with the name. I just used TextBoxFor helper instead of the TextBox helper. This way, there is no need to pass in a name and MVC will just figure it out. Actually the only difference in the useNativeUnobtrusiveAttributes switch is we pass MVC your extended attributes instead of the original attributes.

All tests pass.