Go 1.4+ has https://golang.org/pkg/net/http/#Request.BasicAuth
method for http.Request and it was requested by CoreOS(kelsey) [1]
with the same functionalities. If dex's Go development is being done
in Go 1.4 or later, we should use the standard library.

Thanks!

---
[1] https://codereview.appspot.com/76540043/