The previous test certificates use 1024-bit RSA keys and SHA-1 for
signatures. They are somewhat deprecated. This commit updates the
certificates with RSA-2048 and SHA-256.

MesaLink requires an SNI set in client session. This commit sets the SNI
in the test cases. Note OpenSSL is not affected by this change.

This commit adds a new TLS backend in mesalink_ssl_helper.cpp.
openssl/*.h are replaced with mesalink/openssl/*.h in some files.

This commit adds an option "--with-mesalink" to config_brpc.sh, which
enables MesaLink as a TLS backend instead of OpenSSL.

add discovery client

Feature: Add always_print_primitive_fields flags into Controller and …

Update .bazelrc

set ture if dumps all fields to json in protobuf3.

Support Prometheus output

update avalanche.md

string_splitter supports embedded '\0' characters and separator can be '\0'

bug fix: consul ns thread can not quit