Collapse user activity items loaded from message bus

User activity items that get special grouping treatment come out a bit wrong when loaded on-demand from message bus. While this leads to kind of funny messages...

![borked activity item](https://f.cloud.github.com/assets/449006/183503/a1455ede-7c9e-11e2-9425-e05f5b706ef9.png)

...performing the "grouping" on the newly loaded item helps to maintain a consistent display of likes, etc.