avoid having the .gitattributes skeleton influence the export

Author: splitbrain

Skeletor.php

@@ -104,7 +104,7 @@ public function addBasics()
         $this->loadSkeleton('info.txt', $this->type . '.info.txt');
         $this->loadSkeleton('README');
         $this->loadSkeleton('LICENSE');
-        $this->loadSkeleton('.gitattributes');
+        $this->loadSkeleton('_gitattributes', '.gitattributes');
     }
 
     /**