Adjust debian rules to account for new modules.xml

Not included in the original PR, and to my shame I hadn't noticed.

build/debian/rules

@@ -23,5 +23,6 @@ install/openfire::
 	cp -r $(TARGET)/resources/database $(OPENFIRE)/resources/database
 	cp $(TARGET)/conf/openfire.xml $(ETCDIR)
 	cp $(TARGET)/conf/security.xml $(ETCDIR)
+	cp $(TARGET)/conf/modules.xml $(ETCDIR)
 	cp -r $(TARGET)/resources/security $(ETCDIR)/security
 	cp -r $(TARGET)/plugins $(VARDIR)/plugins