VOTING_MATURITY doesn't work as expected

[dlh]

A player could not issue votes, even if they had been playing on the server for longer than VOTING_MATURITY.

* When a player entered a server, its voter would not be created, because the player was not yet on a team.
* The voter would be created when the player issued a new vote, with the reference time being when the voter was created.

The reference time for issuing votes is now when the player joined the server.