Multiple tos

[ArronKing]

Adds the ability to use multiple to addresses.

At present:

routeNotificationForMail(Notification $notification)
{
  return [
    'john@example.com' => 'John Doe',
    'jane@example.com' => 'Jane Doe',
  ];
}

Only sends an email to john@example.com

The PR changes this and would send to both john@example.com and jane@example.com. It is backwards compatible with single recipients.

[aozisik]

Looks good to me @ArronKing. Thanks!

[ArronKing]

That's perfect, thanks very much @aozisik