feat(lib/*.js): change map-stream to through2

* update through2 to ^0.5.1
Quick fix for [this](https://github.com/tomchentw/vinyl-fs/commit/8bf8612702e228fcc0c678acafe7634f2c6b269b) and [test case](https://github.com/tomchentw/vinyl-fs/commit/595e96e45f12fc868f9ce256d0421da7f4932843).