Set null default value to max

[pabloveintimilla]

This avoid this error:
Type error: Too few arguments to function Avanzu\AdminThemeBundle\Event\NotificationListEvent::__construct(), 0 passed in /var/www/html/cti/vendor/avanzu/admin-theme-bundle/Controller/NavbarController.php on line 39 and exactly 1 expected

[shakaran]

@pabloveintimilla instead set null as default, probably it is more suitable set 0 as integer? Also I am seeing a getTotal() and getMax(), I am not sure if the getMax() is redundant or it never should be major than total (i didn't inspect or check this part of code still)

[pabloveintimilla]

@shakaran i understand that the variable "max" is useful to set maximun number of notifications displayed in panel, is correct?. If this is correct y recommend set null that represent without limit

[shakaran]

@pabloveintimilla after check the code, it seems that it is not really used in any place that set the maximum of notification.

I update other events using getMax() that probably have the same issue.
f139524

And added some phpdoc:
d273c83

Thanks for your contribution!