add unit test to make sure the next tier is tried in the tracker list when the one ahead of it fails
add unit test to make sure the next tier is tried in the tracker list when the one ahead of it fails

git-svn-id: 6df6a9299d9fe08e1e18eb0c01ae615f7df02338@6051 a83610d8-ad2a-0410-a6ab-fc0612d85776

NoGare/libtorrent-rasterbar,NoGare/libtorrent-rasterbar,NoGare/libtorrent-rasterbar,NoGare/libtorrent-rasterbar,NoGare/libtorrent-rasterbar,NoGare/libtorrent-rasterbar