Activity page

Hi,
I added a feature that allows you to link directly to a service's activity from the /activities page by storing the key for the service. This has been useful for me to quickly delete a  bad activity, or just to view it.

You might even be able to start dedupe already synced activities based on the ServiceKey.

Let me know what you think.

-Blake
I don't know if it happens anywhere, but using mutable collections as default parameters isn't the best idea because the same instance ends up getting shared between all calls to the method.