message: feat(core): add distinct "unit-test" target
  This allows running the unit tests with nyc coverage and enables
  passing arguments (like `--bail`) to mocha
  Issue:
diff: "webpack-dev": "webpack --progress --colors --env.dev",
  "webpack-test": "webpack --progress --colors --env.test",
  "webpack-prod": "webpack --progress --colors --env.prod",
  - "test": "npm run unit-test",
  - "unit-test": "nyc -- mocha \"test/unit/*.ts\" \"test/unit/**/*.ts\" \"test/v2/unit/*.ts\" \"test/v2/unit/**/*.ts\"",
  + "test": "npm run coverage",
  + "unit-test": "mocha \"test/unit/*.ts\" \"test/unit/**/*.ts\" \"test/v2/unit/*.ts\" \"test/v2/unit/**/*.ts\"",
  + "coverage": "nyc -- npm run unit-test",
  "integration-test": "nyc -- mocha \"test/v2/integration/**/*.ts\"",
  "browser-test": "karma start karma.conf.js",
  "lint": "eslint --quiet .",
  