js: Set default app name to be location.host

Change-Id: Icd4cffaa1e0c477a99db961f919d0b4f07964dde
diff --git a/src/vanadium.js b/src/vanadium.js
index 865f8f9..63923b1 100644
--- a/src/vanadium.js
+++ b/src/vanadium.js
@@ -15,7 +15,7 @@
 var vlog = require('./lib/vlog');
 
 var defaults = {
-  appName: 'untitled webapp',
+  appName: require('is-browser') ? window.location.host : 'untitled js app',
   authenticate: isBrowser,
   logLevel: vlog.levels.WARN,
   wspr: process.env.WSPR || (isBrowser ? null : 'http://localhost:8124')