Sleep 1 second by default in case of 429 response

There were cases, when client subsequently recieved 429 responses with
retry-after=0, eg.

* retries: 0, sleep: 1
* retries: 1, sleep: 0
* retries: 2, sleep: 0

On the next try you'll get error:
> Your request count (44) is over the allowed limit of 40.

Author: yukoff

lib/Tmdb/HttpClient/Adapter/GuzzleAdapter.php

@@ -62,6 +62,12 @@ public function registerSubscribers(EventDispatcherInterface $eventDispatcher)
                     // Adding 20% of the waiting time as it seems to be the best result without getting two blocking reqs.
                     $sleep = (int) $event->getResponse()->getHeader('retry-after') * 1.2;
 
+                    /**
+                     * @see https://github.com/php-tmdb/api/issues/154
+                     * Maybe it's even better to set it to $number value
+                     */
+                    if (0 === $sleep && $number) $sleep = 1;
+
                     if ($sleep >= 0) {
                         return $sleep * 1000;
                     }