implement bandwith_limit changes necessary since Gluon 2016.1

in Gluon 2016.1 the bandwith limits stated in simple_tc.mesh-vpn have been moved to the fastd_mesh_vpn section (https://gluon.readthedocs.io/en/v2016.1/releases/v2016.1.html#site-changes)
this fixes newly flashed nodes not having the bandwith_limit activated by default and readds the currently missing default limits

site.conf

@@ -90,6 +90,11 @@
 				},
 			},
 		},
+		bandwidth_limit = {
+			enabled = true,
+			egress = 500,
+			ingress = 8000,
+		},
 	},
 
 	opkg = {
@@ -152,15 +157,6 @@
 		branch = 'testing',
 	},
 
-	simple_tc = {
-		mesh_vpn = {
-			ifname = "mesh-vpn",
-			enabled = true,
-			limit_egress = 500,
-			limit_ingress = 8000,
-		},
-	},
-
 	config_mode = {
 		geo_location = {
 			show_altitude = false,