[BUGFIX] Always enforce case sensitive file system

This prevents file path and identifier to become lowercased on
development system.

Classes/Resource/Driver/FileFillDriver.php

@@ -128,6 +128,14 @@ public function dumpFileContents($identifier)
         $this->originalDriverObject->dumpFileContents($identifier);
     }
 
+    /**
+     * @return bool
+     */
+    public function isCaseSensitiveFileSystem()
+    {
+        return true;
+    }
+
     /**
      * @param string $fileIdentifier
      * @return bool