Don't typecast parsed document if I want

The brief history why I've commited it - I can't parse properly document like this:

```xml
	<global-settings>
		<group>
			<name>Global CloudFlare Settings</name>
			<setting id="host_api_key" type="string" default-value="">
				<name>Host API Key</name>
				<description>Your hosting provider API key.  If you do not have one, apply for one at https://www.cloudflare.com/certified-partners</description>
			</setting>
		</group>
	</global-settings>
```

```ruby
=> MultiXml.parse(xml)
=> {"global_settings"=>
  {"group"=>{"name"=>"Global CloudFlare Settings", "setting"=>""}}}
```