one more convenience method.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@10077 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/XmlFile.java

@@ -148,6 +148,10 @@ public final class XmlFile {
         return file.exists();
     }
 
+    public void delete() {
+        file.delete();
+    }
+    
     public void mkdirs() {
         file.getParentFile().mkdirs();
     }