redirect! (Merb::Authentication::Strategy)

    # File lib/merb-auth-core/strategy.rb, line 138
          def redirect!(url, opts = {})
            self.headers["Location"] = url
            self.status = opts[:permanent] ? 301 : 302
            self.status = opts[:status] if opts[:status]
            self.body   = opts[:message] || "<div>You are being redirected to <a href='#{url}'>#{url}</a></div>"
            halt!
            return true
          end