Modify join and leave an item in datastore. TODO: Implement GCM when joining and leaving a group. Return HTTP.StatusNotFound if an item is deleted when the owner leaves the group. Implement other Google Cloud Messaging functions according to this application, ex, item details, attend and leave an item.
Modify join and leave an item in datastore. TODO: Implement GCM when joining and leaving a group. Return HTTP.StatusNotFound if an item is deleted when the owner leaves the group. Implement other Google Cloud Messaging functions according to this application, ex, item details, attend and leave an item.

junglesung/Aliza