Use data: { confirm: 'Text' } to fix confirm: 'Text' deprecation

Fixes this deprecation warning:

```
DEPRECATION WARNING: :confirm option is deprecated and will be removed from Rails 4.1. Use 'data: { confirm: 'Text' }' instead. (called from realtime at /Users/rpai/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/benchmark.rb:296)
```