tagomoris/fluent-plugin-sampling-filter — pull request #1 by harukasan (2014-01-20 12:02:04+00:00)
Title: allow no add_prefix

This PR allows config like below:
```

interval 10
add_prefix
remove_prefix full

...

```

But I have one matter.
Because `add_prefix` has default parameter, we need specify `add_prefix` alone to make blank.
This behavior looks odd. Do you have any idea?