Clean up outdated locally stored user profiles

[HenrikJannsen]

We keep locally user profiles which have expired their TTL of 15 days.

The profile age data has a TTL of 30 days, and the other reputation data of 100 days.

Thus if the locally stored user profile is older than 30 days we show N/A as profile age. If it is older than 100 days, the reputation data will get removed and the reputation score will drop.

We should consider to either clean up user profiles which have expired, or mark them in the UI (visible mainly in the reputation score list) as expired if we want to keep them.

For privacy reasons I guess purging them is the preferred way.