Generalize delete views by extracting success_url
Delete stuff on click
Fix HTML template error on Someday / Maybe page

There is no plan to embed form fields on the list.  It should have been
deleted when copying stuff list template file.
Add link on maybe/someday item for update

Generalize IsActionableView in order to share the view for reviewing
stuff items.
Rename ActionUpdate to TextUpdate

TextUpdate is going to be shared when updating text of varios type of
'Thing' objects.
Show/hide buttons for the right category

Some actions does not make sense for a category of Thing object.
Add icons to buttons on "Is Actionable?" page
Update next action item as same as maybe item

Next action item can turn into maybe item.