message: Make package json format consistent.
diff: "canvas",
  "2d"
  ],
  - "contributors": [
  - {
  - "name": "erik",
  - "email": "errorrik@gmail.com"
  - }
  - ],
  "repository": {
  "type": "git",
  "url": "https://github.com/ecomfe/zrender.git"
  