npm v3.4.1 (2015-11-12) 默认安装最新版本

https://github.com/npm/npm/releases/tag/v3.4.1

说 npm install 安装的改成最新的版本, 无论是什么样的版本... 不知道影响是多大.. 围观

When you run npm install foo, you probably expect that you'll get the latest version of foo, whatever that is. And good news! That's what this change makes it do.

We think this is what everyone wants, but if this causes problems for you, we want to know! If it proves problematic for people we will consider reverting it (preferrably before this becomes npm@latest).