AsyncTask to download canteens and JPO CanteenItem.

The AsyncTask connects to the Heroku backend. Using the CanteenItem object to host the data and be the backend model of our ListView
JPO to be used in the ListView
Starting background thread, and starts the WeekListActivity whenever a Item is pushed.
This activity is not yet done. Have deserialized the canteenitem and will use that to further start a new background thread to collect the weekly menu items.