Use http-conduit for url downloads by default, annex.web-options enables curl

* For url downloads, git-annex now defaults to using a http library,
  rather than wget or curl. But, if annex.web-options is set, it will
  use curl. To use the .netrc file, run:
    git config annex.web-options --netrc
* git-annex no longer uses wget (and wget is no longer shipped with
  git-annex builds).

Note that curl is always run in silent mode, since the new API for
download has a MeterUpdate and doesn't make way for curl progress
output. It might be worth writing a parser for curl's progress output
to update the meter when using it, but I didn't bother with this edge
case for now.

This commit was supported by the NSF-funded DataLad project.

Remote/BitTorrent.hs

@@ -193,13 +193,13 @@ downloadTorrentFile u = do
 		( return True
 		, do
 			showAction "downloading torrent file"
-			showOutput
 			createAnnexDirectory (parentDir torrent)
 			if isTorrentMagnetUrl u
 				then do
 					tmpdir <- tmpTorrentDir u
 					let metadir = tmpdir </> "meta"
 					createAnnexDirectory metadir
+					showOutput
 					ok <- downloadMagnetLink u metadir torrent
 					liftIO $ removeDirectoryRecursive metadir
 					return ok
@@ -208,7 +208,7 @@ downloadTorrentFile u = do
 					withTmpFileIn misctmp "torrent" $ \f h -> do
 						liftIO $ hClose h
 						ok <- Url.withUrlOptions $ 
-							liftIO . Url.download u f
+							liftIO . Url.download nullMeterUpdate u f
 						when ok $
 							liftIO $ renameFile f torrent
 						return ok