Segfault when using `Liberic.config` in Rails 5.0.0

When calling

``` ruby
Liberic.config.data_path = '/tmp'
```

A segfault occurs. This happens because the instance of config is created inside the `Liberic` module when loading the gem or something.

Everything works when creating a new instance inside Rails, like

``` ruby
c = Liberic::Config.new
c.data_path = '/tmp'
```
