Allow seconds to be passed explicitly in memcached.

[sauravkumal]

I am not sure if there is already a solution to this but didn't find any. in MemcachedStore.php we have

public function put($key, $value, $seconds)
{
    return $this->memcached->set(
        $this->prefix.$key, $value, $this->calculateExpiration($seconds)
    );
}

When the second is passed to memcached server, a timestamp is sent instead. And i noticed that over time, if the memcached time starts drifting, the expiry doesn't trigger as intended. I manually bypassed the $this->calculateExpiration($seconds), passed the expiry in seconds and was able to get accurate expiry regardless of the drift. So just an idea if we should add this feature, or should I keep doing it as i am doing.