Respect $options when $server is null in Connection constructor

lib/Doctrine/MongoDB/Connection.php

@@ -76,7 +76,7 @@ public function __construct($server = null, array $options = array(), Configurat
     {
         if ($server instanceof \MongoClient || $server instanceof \Mongo) {
             $this->mongo = $server;
-        } elseif ($server !== null) {
+        } else {
             $this->server = $server;
             $this->options = $options;
         }