def set_remote_url(name, url)
      url = url.repo.path if url.is_a?(Git::Base)
      self.lib.remote_set_url(name, url)
      Git::Remote.new(self, name)
    end
sets the url for a remote
url can be a git url or a Git::Base object if it's a local reference

@git.set_remote_url('scotts_git', 'git://repo.or.cz/rubygit.git')