member change

是否需要实现member change功能？ 我看Raft论文中对这个描述的不是很详细，或许可以利用leveldb的多版本控制来复制一些log到新的成员上去，这样可以不用停止服务，然后再根据论文中的方案进行成员变更。
昨天暴了一个raft成员变更算法的bug,　https://groups.google.com/forum/#!topic/raft-dev/t4xj6dJTP6E

No source files, tests, or entry points are named. Start by locating the repository's Raft membership and log-replication code, then read the Raft paper and the linked raft-dev discussion; done would require an agreed member-change design, implementation scope, and tests for the reported algorithm bug.

Written by the indexing model from the issue text.