Add more timing in the profile, add useProfiler config variable

Default to useProfiler:true in staging and development

config/environments/development.js.example

@@ -63,6 +63,10 @@ var config = {
         port: 6082,
         ttl: 86400
     }
+    // If useProfiler is true every response will be served with an
+    // X-Tiler-Profile header containing elapsed timing for various 
+    // steps taken for producing the response.
+    ,useProfiler:true
 };
 
 module.exports = config;