message: update polymer-workspaces v2.1.0
diff: "mkdirp": "^0.5.1",
  "mz": "^2.6.0",
  "polymer-analyzer": "~2.3.0",
  - "polymer-workspaces": "^2.0.0",
  + "polymer-workspaces": "^2.1.0",
  "recast": "^0.12.4",
  "rimraf": "^2.6.1",
  "semver": "^5.3.0",
  