Fixes #72: Use r instead of r+, read streams should only be readable …

…in the Local adapter

src/Adapter/Local.php

@@ -154,7 +154,7 @@ public function writeStream($path, $resource, $config = null)
      */
     public function readStream($path)
     {
-        $stream = fopen($this->prefix($path), 'r+');
+        $stream = fopen($this->prefix($path), 'r');
 
         return compact('stream', 'path');
     }