[Symfony 2.8] Add rename of Simple(Pre|Form)AuthenticatorInterface from Core to Http namespace

[TomasVotruba]

Symfony 2.8 deprecated the Simple*AuthenticatorInterface interfaces in the Security\Core namespace and moved them to Security\Http. They were removed later, so the rename is a required upgrade step.

Added to composer-based.php, bonded to symfony/symfony >=2.8.

-use Symfony\Component\Security\Core\Authentication\SimplePreAuthenticatorInterface;
+use Symfony\Component\Security\Http\Authentication\SimplePreAuthenticatorInterface;

-use Symfony\Component\Security\Core\Authentication\SimpleFormAuthenticatorInterface;
+use Symfony\Component\Security\Http\Authentication\SimpleFormAuthenticatorInterface;

Ref: https://github.com/symfony/symfony/blob/2.8/UPGRADE-2.8.md#security