v1.5

1. create gas user white list
2. create private key encryption file storage

v1.4

1. remove not used native contract code
2. optimize log print

v1.3

Increase block gaslimit to 40,000,000
Consensus block frequency reduce from 1s/block to 3s/block
Add gas transfer management
Add p2p whitelist configuration

v1.1_hotfix

Fix the long pending of transaction issue.

v1.1

add gas price limit

v1.0

add Consensus vote (#48)

* add consensus vote

* add unitest and fix bug

* remove unused code

Co-authored-by: zhang menghang <zhangmenghang@zhangs-MacBook-Pro.local>