Comment 0 for bug 1179425

The doc string in exception.py of Keystone can be returned with __doc__method, but cannot realize the internationalization.

/v2.0/tokens
{
    "error": {
        "message": "Expecting to find username or userId in passwordCredentials. The server could not comply with the request since it is either malformed or otherwise incorrect. The client is assumed to be in error.",
        "code": 400,
        "title": "Bad Request"
    }
}
{
    "error": {
        "message": "The request you have made requires authentication.",
        "code": 401,
        "title": "Not Authorized"
    }
}
{
    "error": {
        "message": "Invalid user / password",
        "code": 401,
        "title": "Not Authorized"
    }
}
The message in error should be translated.