Nicer error when fail to create user in gandalf

Shows user email and the gandalf server address

    2014/12/27 07:30:28 ERROR: error trying to create user "user@example.com" in gandalf (http://127.0.0.1:8000): Failed to create user in the git server: Failed to connect to Gandalf server, it's probably down.
I think it's a habit of mine to quote user input stuff in case it's blank. You can change to %s if you want or I can do it when I'm back at a keyboard.