Fix server groups being written without proper identity settings

Fixes CLIENT-94

Change-Id: Ie4379d09bc256222f0844a777dc385b0cae74530
Reviewed-on: http://gerrit.dmdirc.com/1583
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>
Reviewed-by: Greg Holmes <greg@dmdirc.com>

src/com/dmdirc/addons/serverlists/io/ServerGroupWriter.java

@@ -61,6 +61,7 @@ public class ServerGroupWriter {
      */
     public void write(final ServerGroup group) {
         final Set<String> sections = identity.getDomains();
+        sections.remove("identity");
 
         identity.setOption("identity", "name", group.getName() + " servergroup");