Cap max session time to a safe value.

[pavelhoral]

This change fixes issues with immediate expiration of agent sessions created with com.iplanet.am.session.agentSessionIdleTime system property set to a non-zero value.

The original issue was that when the agentSessionIdleTime was set, then max session time was set to Long.MAX_VALUE, which caused value overflow in getMaxSessionExpirationTime and the session was immediately marked as expired.

The issue led to a quite strange behavior of not including tokenId field in REST /authentication response:

{
    "message": "Authentication Successful",
    "successUrl": "/auth/console",
    "realm": "/"
}

[karelmaxa]

LGTM.