rails/rails — pull request #16397 by y-yagi (2014-08-05 00:21:30+00:00)
Title: Fix for custom_configuration when use only one key

When I set only one key in custom_configuration, cannot acquire a value.

```ruby
config.x.super_debugger = true
```

```ruby
Rails.configuration.x.super_debugger # => {}
```

I think that able to acquire a value is good, how about?