Add alert about node vs raven-js when it seems like a browser env

lib/client.js

@@ -23,6 +23,11 @@ nodeUtil.inherits(Raven, events.EventEmitter);
 
 extend(Raven.prototype, {
   config: function config(dsn, options) {
+    // We get lots of users using raven-node when they want raven-js, hence this warning if it seems like a browser
+    if (typeof window !== 'undefined' && typeof document !== 'undefined' && typeof navigator !== 'undefined') {
+      utils.consoleAlert('This looks like a browser environment; are you sure you don\'t want Raven.js for browser JavaScript? https://sentry.io/for/javascript');
+    }
+
     if (arguments.length === 0) {
       // no arguments, use default from environment
       dsn = process.env.SENTRY_DSN;