title: How to suppress automatic quoting of strings with ruamel.yaml
body: <p>I am using ruamel.yaml to generate "recipes" for a build tool, which accepts a non-standard superset of yaml.  I'm getting some undesirable output, and my searches for how to disable this have come up dry.  Here's an example:</p>
  
  <pre><code>import ruamel.yaml as ryaml
  
  test = ryaml.comments.CommentedMap(requirements={'host': ['abc', 'def   # [something]']})
  print(ryaml.dump(test, Dumper=ryaml.RoundTripDumper,
                                              default_flow_style=False,
                                              default_style="",
                                              width=200))
  </code></pre>
  
  <p>This automatically quotes the thing that is not valid yaml (which honestly is quite sane default behavior):</p>
  
  <pre><code>requirements:
    host:
      - abc
      - 'def   # [something]'
  </code></pre>
  
  <p>I really need it to not add those single quotes around the non-standard line.  I don't expect ruamel to be able to parse it back in, just dump it.</p>