Add command notification

Update client.cc

Update epoll_manager.h

Cleanup command.cc

Update epoll_manager.cc

Update command.h

Update conn.h

Create README.md

Add server connection using loopback address and port 6969

Disable printf buffering

Refactor Command struct

Partial read handling in RedisServer::handleRead()

Improve logger commands

Refactor Conn struct with additional parameters

Refactor Command and EpollManager classes