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
Everything else in ActivityRecords is keyed on the service provider's ID (e.g. `strava`), so it'd probably be a good idea to do that here, too. Though, hat will further entrench the idea of one connection per service... Oh well.