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/Git.hs

@@ -252,7 +252,7 @@ tryGitConfigRead autoinit r
 		v <- liftIO $ withTmpFile "git-annex.tmp" $ \tmpfile h -> do
 			hClose h
 			let url = Git.repoLocation r ++ "/config"
-			ifM (Url.downloadQuiet url tmpfile uo)
+			ifM (Url.download nullMeterUpdate url tmpfile uo)
 				( Just <$> pipedconfig "git" [Param "config", Param "--null", Param "--list", Param "--file", File tmpfile]
 				, return Nothing
 				)