Could cascade aliases

[yola-0316]

This feature may help write multip alias.

  "aliases": {
    "common": ["license", "readme", "editorconfig", "gitignore"],
    "node": ["common", "npm"],
    "frontend": ["node", "eslint"],
    "backend": ["node", "foo"]
  }

I see in runAlias before runTask not judge task is a alias, may be should do it.

[sapegin]

Good idea! Feel free to send a pull request! 👾