Merge pull request EOSIO#3434 from pacificcode/eosio_build_centos

CentOS: Boost version 1.67

Merge pull request EOSIO#3292 from EOSIO/discard-bad-peer-info

Remove bad peer addresses from the connection list immediately.

Merge pull request EOSIO#3210 from EOSIO/gh#2099-get-block

get block display of old structs

Merge pull request EOSIO#3142 from EOSIO/net_sync_broadcast_on_chain_…

…acceptance

Broadcast transactions immediately upon chain acceptance

Merge pull request EOSIO#2967 from EOSIO/slim

Merge slim into master

Merge pull request EOSIO#2165 from larryk85/fix/create_account_fails

Fix eos EOSIO#2160

Merge pull request EOSIO#1986 from EOSIO/bios-use-well-known-key

restore the default producer key pair for the bios producer

Merge pull request EOSIO#1880 from taokayan/txn_test_plugin

fix txn_test_gen_plugin for stress test(DAWN-562)