Suspended abilities leave no mod-visible history

[cellio]

When a moderator suspends an ability, the user receives an inbox notification (with a customizable message from the moderator) and the ability shows as suspended on the mod "privileges" page. However, there's no other record, which poses two problems:

1. Other moderators can't see the message that was sent to the user.
2. After the suspension expires, the fact that it ever happened is not visible. If the problem recurs, moderators can't review the history.

Let's record ability suspensions, at least, as annotations. Perhaps they should also be recorded in full user activity, because suspensions are.

[luap42]

As far as I can tell, the effort required for this issue should be quite low. However some design considerations and some fuzzying might need to be done, hence I'm marking this as average complexity, although it most definitely is on the lower end of averagely complex issues... ^^