Before this change serving bucket based objects
`[remote:bucket]/path/to/object` would fail with 404 not found.
This was because the leading `/` in `/path/to/object` was being passed
to NewObject.
Tests have been randomly failing with messages like
listen tcp 127.0.0.1:51778: bind: address already in use
Rework all the test servers so they choose a random free port on
startup and use that for the tests to avoid.
If `--rc-user` or `--rc-pass` is set then the URL that is opened with
`--rc-files` will have the authorization in the URL in the
`http://user:pass@localhost/` style.
