merged test_tracker tweak from RC_0_16

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@9823 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda
polish test_remap_files

git-svn-id: http://libtorrent.googlecode.com/svn/trunk@9824 f43f7eb3-cfe1-5f9d-1b5f-e45aa6702bda