GUI-25 support account,username params on url to pre-fill euca login form

support account,username params on url to pre-fill euca login form

https://eucalyptus.atlassian.net/browse/GUI-25
@dkavanagh: The json_options needs to be moved into the LoginView's init() method to avoid 500 errors if login fails due to wrong username, unavailable host, etc. Also, we should rename it controller_options_json to be consistent with the rest of the console.