avoid auto unzip tar.gz files
avoid auto unzip tar.gz files

fix https://github.com/chrislusf/weed-fs/issues/90

chrislusf/seaweedfs,chrislusf/seaweedfs,k85169336/seaweedfs,k85169336/seaweedfs,hxiaodon/seaweedfs,chrislusf/seaweedfs,chrislusf/seaweedfs,hxiaodon/seaweedfs