Fast to slowly spec

```
 paperclip $ rspec spec/paperclip/integration_spec.rb --profile 1
Testing against version 4.1.7
.........................[deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this message.
.........

Finished in 15.19 seconds (files took 0.60155 seconds to load)
34 examples, 0 failures

Top 1 slowest examples (9.54 seconds, 62.8% of total time):
  Paperclip Many models at once does not exceed the open file limit
    9.54 seconds ./spec/paperclip/integration_spec.rb:18
```

to

```
 paperclip $ rspec spec/paperclip/integration_spec.rb --profile 1
Testing against version 4.1.7
.........................[deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this message.
.........

Finished in 10.95 seconds (files took 0.59585 seconds to load)
34 examples, 0 failures

Top 1 slowest examples (5.33 seconds, 48.7% of total time):
  Paperclip Many models at once does not exceed the open file limit
    5.33 seconds ./spec/paperclip/integration_spec.rb:18
```

at trim indent
Unused block argument - `i`. You can omit the argument if you don't care about it.