OPER command is related with config file

[pablo-lamtenzan]

@ClemaX you did the config file, can u add (if is not done yet) a field for an admin nickname with an admin password ? Those values will be used to init the member "admin" a std::pair in irc::Server. Thanks.

[pablo-lamtenzan]

CHANGE: Now irc::Server definition has an instance of irc::ServerAdmin is needed to be init by default or overwritten in the configuration file.