RLogin should support auto-account creation

[paladine]

Upon initial Rlogin connection, if the user doesn't exist, we should support auto creating the accounts, using the default creation key set defined the config file.

It would be useful to have a config option that enables this auto-rlogin-account-creation feature, defaulting to true.

[tuday2]

As part of this we could remove the checks for haskey(), haskeym() and uidkey() (in majorbbs.cs) for missing rlogin user

            //If the user isnt registered on the system, most likely RLOGIN -- so apply the default keys
            if (_accountRepository.GetAccountByUsername(userName) == null)
            {
                keys = _configuration.DefaultKeys;
            }
            else
            {
                var accountKeys = _accountKeyRepository.GetAccountKeysByUsername(userName);
                keys = accountKeys.Select(x => x.accountKey);
            }