We have only one role, so let's get rid of the unneeded method.
Now we are in a better place to get rid of Spree::Role and replace it
with a simple boolean.
Simply rendering the edit form on the posted path is problematic. For example if you refresh the path you get a 404.
But if there's errors, we want to render the form with unsaved values so you can see the errors and try again.
