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
Good point. I moved everything under Presence, where it's already keyed by provider's ID.
This does leave it open to problems, say a user unlinks runkeeper account A then links runkeeper account B then the links won't work. Though that is not a normal use case.