Better handle single table inheritance for resource redirects

Use #becomes method to ensure that the record is cast as the resource class before redirection so that the correct (parent) url helper is chosen

Author: rsmithlal

app/controllers/better_together/resource_controller.rb

@@ -26,7 +26,7 @@ def create
       authorize_resource
 
       if @resource.save
-        redirect_to @resource, notice: "#{resource_class.model_name.human} was successfully created."
+        redirect_to @resource.becomes(resource_class), notice: "#{resource_class.model_name.human} was successfully created."
       else
         render :new, status: :unprocessable_entity
       end
@@ -36,7 +36,7 @@ def update
       authorize_resource
 
       if @resource.update(resource_params)
-        redirect_to @resource, notice: "#{resource_class.model_name.human} was successfully updated."
+        redirect_to @resource.becomes(resource_class), notice: "#{resource_class.model_name.human} was successfully updated."
       else
         render :edit, status: :unprocessable_entity
       end