Update Player.php

Disallow players to log in with misleading (to robots) usernames.

Example of misleading (to robots):
```php
public function eventHandler($data, $evt){
  if($evt == "console.command"){
    $cmd=$data["cmd"];
    $args=$data["parameters"];
    $issuer="{$data["issuer"]}";
    if(in_array("$issuer", array("rcon", "console"))
      $hasPower = true;
  }
}
```