Allow to use domain whose prefix is not misskey

gulpfile.ts

@@ -124,6 +124,7 @@ gulp.task('build:client:script', () =>
 		.pipe(replace('VERSION', JSON.stringify(version)))
 		.pipe(replace('API', JSON.stringify(config.api_url)))
 		.pipe(replace('ENV', JSON.stringify(env)))
+		.pipe(replace('HOST', JSON.stringify(config.host)))
 		.pipe(isProduction ? uglify({
 			toplevel: true
 		} as any) : gutil.noop())

src/web/app/boot.js

@@ -27,9 +27,7 @@
 	//   misskey.alice               => misskey
 	//   misskey.strawberry.pasta    => misskey
 	//   dev.misskey.arisu.tachibana => dev
-	let app = url.host == 'localhost'
-		? 'misskey'
-		: url.host.split('.')[0];
+	let app = url.host === HOST ? 'misskey' : url.host.substr(0, -HOST.length);
 
 	// Detect the user language
 	// Note: The default language is English