Support using a seeds host for bootstrapping connections.

core/core.js

@@ -64,6 +64,11 @@ const k_global_settings = {
 				: undefined,
 		description: 'Blobs older than this will be automatically deleted.',
 	},
+	seeds_host: {
+		type: 'string',
+		default_value: '',
+		description: 'Hostname for seed connections.',
+	},
 };
 
 let gGlobalSettings = {