Revert "Fix writing NLog properties in Log4JXmlEvent"

This reverts commit 7d48bdb23ff5f59974a9cf3595a4a0a76515e3c2.

Conflicts:
	src/NLog/LayoutRenderers/Log4JXmlEventLayoutRenderer.cs
Merge pull request #215 from Xharze/Log4JXmlBug

Revert "Fix writing NLog properties in Log4JXmlEvent"