Raise or log unpermitted params.

For context see: https://github.com/rails/strong_parameters/pull/75#issuecomment-12255994

* Developers can choose to log or raise on unpermitted parameters.
* Default is to log in test and development, otherwise do nothing.

To enable the exception:

```ruby
config.action_controller.action_on_unpermitted_params = :raise
```

This is ultimately in response to: https://github.com/rails/strong_parameters/issues/66

I will port this work over to https://github.com/rails/strong_parameters once discussion here is complete.