(Ruby) Add option to parse with ALLOW_UNESCAPED_CONTROL_CHARS

[Mekk]

It would be great if JrJackson::Ruby allowed one to specify some option which would cause parsing with ALLOW_UNESCAPED_CONTROL_CHARS. So, in particular, it would be possible to parse json like

{
    "message": "This contains
newlines, what maybe isn't 100% formal,
but is eye friendly"
}

If I understand correctly (my java is … fairly limited) this is about paching somewhere around https://github.com/guyboertje/jrjackson/blob/master/src/main/java/com/jrjackson/JrJacksonRuby.java#L75 so it (conditionally) enables this feature using approach described in FasterXML/jackson-core#586

Rationale: I got here while digging whether logstash could parse json's with unescaped newlines ( logstash-plugins/logstash-filter-json#53 )