Remove deprecated use of :confirm in scaffold templates

The `:confirm` option has been deprecated and will be removed in Rails 4.1.

This changes all instances of `:confirm` in the scaffold templates from:
```ruby
:confirm => 'Are you sure?'
```
to
```ruby
:data => { confirm: 'Are you sure?' }
```

According to https://github.com/rails/rails/pull/6613 it was deprecated in rails 3.2