hide Batmanv15 domain again

This prevents showing the (mandatory) domain selection field in config mode
of the stable firmware. The domain can still be activated via SSH, so that
it can be tested.

domains/ffhb_batv15.conf

@@ -2,6 +2,7 @@
 	domain_names = {
 		ffhb_batv15 = 'Freifunk Bremen - Experimentelles Netz (mit Batman v15)',
 	},
+	hide_domain = true,
 	domain_seed = '9c689a5be0e7610716aa9952d3c186345bd8d72dfa8950977e255e26ea24d978',
 
 	prefix4 = '10.196.0.0/17',