Improve XML rendering in preview

XML can be rendered in the browser fine if we set the correct wrapper.
So rather than trying to do fancy stuff, just return the XML itself wrapped in a <pre> and <code> tag.

Fixes #114

tcwebhooks-core/src/main/java/webhook/teamcity/payload/template/render/XmlToHtmlPrettyPrintingRenderer.java

@@ -1,35 +1,15 @@
 package webhook.teamcity.payload.template.render;
 
-import java.io.IOException;
-import java.io.StringWriter;
 import java.util.Map;
 
-import org.dom4j.Document;
-import org.dom4j.DocumentException;
-import org.dom4j.DocumentHelper;
-import org.dom4j.io.OutputFormat;
-import org.dom4j.io.XMLWriter;
-
 public class XmlToHtmlPrettyPrintingRenderer implements WebHookStringRenderer {
 
 
 	HtmlRenderer htmlr = new HtmlRenderer();
 
 	@Override
 	public String render(String uglyXmlString) throws WebHookHtmlRendererException {
-		try {
-			StringWriter sw = new StringWriter();  
-			Document doc = DocumentHelper.parseText(uglyXmlString);  
-			OutputFormat format = OutputFormat.createPrettyPrint();  
-			XMLWriter xw = new XMLWriter(sw, format);  
-			xw.write(doc);
-			return "<pre><code clas=\"xml\">" + htmlr.render(sw.toString()) + "</code></pre>";
-		} catch (DocumentException ex){
-			throw new WebHookHtmlRendererException(ex);
-		} catch (IOException e) {
-			throw new WebHookHtmlRendererException(e);
-		}
-
+		return  "<pre><code class=\"xml\">" + htmlr.render(uglyXmlString) + "</code></pre>";
 	}
 
 	@Override