Update dash.js

typeof in validation of title was missing.

lib/api/dash.js

@@ -5,7 +5,7 @@ var validate_dashboard = function(dashboard){
         throw new Error('`dashboard` parameter must be an object');
     }
 
-    if(dashboard['title'] != 'string'){
+    if(typeof dashboard['title'] != 'string'){
         throw new Error('`dashboard["title"]` must be a string');
     }