Event moderation list

[Igor Santos]

This list is useful to control the list of events that were not submitted by verified users (#122).

There should be a list of all events with unverified statuses, listing how long those events are in that status. If they're getting old (more than a week?) and their user have not verified their accounts, these events should be manually verified by an admin and manually marked as "verified".

There should be a "counter" badge in the "Manage events" menu entry, displaying how many unverified events there are.