fix some file modes in calls to withTmpFileIn to honor umask

Also audited for other calls to openTempFile, and all are ok,
except for viaTmp which will need further work.

Remote.Directory fixed to set umask mode when writing to an export,
although it has another one using viaTmp that's not fixed.
Will make exports that are published via a http server running as
another user work, for example.

Remote.BitTorrent fixed to set umask mode when downloading the torrent
file. Normally this does not matter as that file does not hang around
after the download, but if a bittorrent download were started by one user,
got interrupted and then another user ran it, this will let them access
the torrent file created by the first user.

Remote/BitTorrent.hs

@@ -202,6 +202,7 @@ downloadTorrentFile u = do
 				else withOtherTmp $ \othertmp -> do
 					withTmpFileIn othertmp "torrent" $ \f h -> do
 						liftIO $ hClose h
+						resetAnnexFilePerm f
 						ok <- Url.withUrlOptions $ 
 							Url.download nullMeterUpdate u f
 						when ok $