Allow users to hibernate their account

[alexanderzatko]

Some users - after a period of activity in Rovas - want to stop participating in the NEO economy, but they do not want to delete their accounts. For example, they might not like having to verify reports that Rovas asks them to do from time to time.

Apparently Rovas should allow account hibernation only after some period of time (say 6 months), since the account owner last published a work report, to avoid abuse of the system.