Use is-tar instead of archive-type

https://github.com/kevva/is-tar
Add test for `strip` option

https://github.com/shinnn/decompress-tar/tree/ce76b87ea62ba0f64cb5b17334
2d0f2310be9b22#strip
Use strip-dirs module for `strip` option

https://github.com/shinnn/node-strip-dirs
Merge pull request #2 from shinnn/master

Fix and improve `strip` option