make butil::BasicStringPiece<T> support string split functions-family

Fix bazel build in macos

testing on 11.0-bigsur

Replace previous hacky impl. of appending postfix to ostream with a safer one and lose the -log_as_json support for glog

add Controller.SessionKV() to record and print session-level KV; Add LOGD/I/W/E/F to print contextual log; Add flag -log_as_json to print logs as valid JSON

Compatibility improvement of protobuf json format and spring http spec

coding style fix in brpc/trackme.cpp

Fix build break for clang 10.0.1

Make doc on StreamOptions consistent with the code

For https naming service, use 443 as default port

add option to allow access methods from default url

update .asf.yaml to change RPC into lowercase

add .asf.yaml to set github about info