Use correct Collection constructor args in GridFS classes

Fixes #135

src/GridFS/GridFSCollectionsWrapper.php

@@ -31,8 +31,8 @@ class GridFSCollectionsWrapper
      */
     public function __construct(Manager $manager, $databaseName, $bucketName, array $collectionOptions = [])
     {
-        $this->filesCollection = new Collection($manager, sprintf('%s.%s.files', $databaseName, $bucketName), $collectionOptions);
-        $this->chunksCollection = new Collection($manager, sprintf('%s.%s.chunks', $databaseName, $bucketName), $collectionOptions);
+        $this->filesCollection = new Collection($manager, $databaseName, sprintf('%s.files', $bucketName), $collectionOptions);
+        $this->chunksCollection = new Collection($manager, $databaseName, sprintf('%s.chunks', $bucketName), $collectionOptions);
     }
 
     public function dropCollections(){

tests/GridFS/FunctionalTestCase.php

@@ -18,7 +18,7 @@ abstract class FunctionalTestCase extends BaseFunctionalTestCase
     {
         parent::setUp();
        foreach(['fs.files', 'fs.chunks'] as $collection){
-            $col = new Collection($this->manager, sprintf("%s.%s",$this->getDatabaseName(), $collection));
+            $col = new Collection($this->manager, $this->getDatabaseName(), $collection);
             $col->drop();
         }
         $this->bucket = new \MongoDB\GridFS\Bucket($this->manager, $this->getDatabaseName());
@@ -28,7 +28,7 @@ abstract class FunctionalTestCase extends BaseFunctionalTestCase
     public function tearDown()
     {
        foreach(['fs.files', 'fs.chunks'] as $collection){
-            $col = new Collection($this->manager, sprintf("%s.%s",$this->getDatabaseName(), $collection));
+            $col = new Collection($this->manager, $this->getDatabaseName(), $collection);
             $col->drop();
         }
         if ($this->hasFailed()) {