1. add support for spring boot starter, spring cloud.
2. use spi to refactor protocol/naming/loadbalance extension.
3. remove shared threadpool for client and server.
4. fix some bugs.

1. support new protocols: public pbrpc, stargate.
2. add trace fileds.
3. different service can set its own thread pool.
4. add consul naming service.
5. RpcContext can set different runtime rpc configs, such as readTimeout.
6. refactor load balance interceptor, so that user can set custom load balance interceptor, such as ribbon.
7. http json client can talk with server which using brpc standard protocol.
8. fix some bugs, like naming update failed etc.

1. support single long connection between client and server.
2. optimize: future return user interface response instead of RpcResponse.
3. fix bug: response sync error for multi-thread.
4. support nshead-json protocol.
5. support cglib proxy instance to register service.

1.refactor http protcol so that http/tcp protocol can use the same port.
2. make RpcClient or RpcServer single instance when it has multi usage in one module.
3. support zookeeper registry.
4. support short connection.
5. fix some bugs, such as fair load balance etc.