Revert 'Fixed Warning: A non-numeric value encountered' from #35. Fixes

#38

File.php

@@ -197,7 +197,7 @@ public function save($data, $id, $tags = array(), $specificLifetime = false)
         $metadatas = array(
             'hash' => $hash,
             'mtime' => time(),
-            'expire' => $this->_expireTime((int)$this->getLifetime($specificLifetime)),
+            'expire' => $this->_expireTime($this->getLifetime($specificLifetime)),
             'tags' => implode(',', $tags),
         );
         $res = $this->_filePutContents($file, serialize($metadatas)."\n".$data);