Adds a title property to each pod.

In the current version of the library each subpod in the final JSON object has a title property, which is extracted from the title attribute of the subpod's original XML. 

I added a title property to each pod, which I also extracted from the title attribute of the pod's XML. 

This makes the pods and subpods share a closer schema.

Also, the title attribute of the pod is generally more useful than the subpod.