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.
Merge pull request #1039 from msabramo/nicer_error_when_fail_to_create_user_in_gandalf

Nicer error when fail to create user in gandalf