v1.0.1 release
This release has the following updates and fixes,
- Fix an asio_service bug that could lead to segmentation fault when shutdown the service
- Add cookie support for log_entry to reduce the chance that leader needs to deserialize state machine requests from log entry
- Add is_reader and replicate_log apis so that the user of raft_server can check leader status and replicate log with cookies
- Add pub/sub for raft_server events, enabling the user code could know about when raft becomes a leader, follower or when the state machine catch up all committed logs