CC-3483: Live Stream: default fade in/out for live stream transition

- done. changing fade value doesn't require LS to restart

python_apps/pypo/liquidsoap_scripts/ls_lib.liq

@@ -15,15 +15,12 @@ def append_title(m) =
   end
 end
 
-default_dj_fade_in = ref 5.
-default_dj_fade_out = ref 5.
-
 def transition(a,b) =
   log("transition called...")
   add(normalize=false,
      [ sequence([ blank(duration=2.),
-                   fade.initial(duration=!default_dj_fade_in, b) ]),
-        fade.final(duration=!default_dj_fade_out, a) ])
+                   fade.initial(duration=!default_dj_fade, b) ]),
+        fade.final(duration=!default_dj_fade, a) ])
 end
 
 def crossfade(s)