sanitize-rails breaks when not provided with a config block

fixed that, defaulting to Sanitize::Config::RELAXED.  might wanna default to rails defaults

```
{ 
  elements: ::ActionView::Base.sanitized_allowed_tags.to_a,
  attributes: { all: ::ActionView::Base.sanitized_allowed_attributes.to_a },
  protocols: { all: ::ActionView::Base.sanitized_allowed_protocols.to_a }
}
```