code: public Options putString(String key, IModel<String> value)
  	{
  		putOption(key, new StringOption(value));
  		return this;
  	}
docs: <p>
  Puts a {@link String} value for the given option name.
  </p>
  
  @param key
  the option name.
  @param value
  the {@link String} value.