make favorites icon a config option
diff --git a/xos/xos_config b/xos/xos_config
index dba4a2e..b86d618 100644
--- a/xos/xos_config
+++ b/xos/xos_config
@@ -42,3 +42,4 @@
 disable_minidashboard=True
 #branding_name=CORD
 #branding_css=/static/cord.css
+#branding_icon=/static/onos-logo.png