message: fix(sample-test): we shouldn't delete node_modules after link
diff: "prelint": "cd samples; npm link ../; npm install",
  "lint": "gts check",
  "prepare": "npm run compile",
  - "samples-test": "cd samples/ && npm link ../ && rm -rf node_modules && npm install && npm test && cd ../",
  + "samples-test": "cd samples/ && npm link ../ && npm test && cd ../",
  "presystem-test": "npm run compile",
  "system-test": "mocha build/system-test --timeout 600000",
  "pretest": "npm run compile",
  