Update project platform to 0.4.0

libgrabber updated project platform to 0.4.0.

@polymer

### Metadata information

```json
{
  "metadata": {
    "packageManager": "github",
    "name": "platform",
    "repo": "polymer/platform",
    "files": {
      "include": ["platform.js", "platform.js.map"],
      "exclude": []
    },
    "path": "/home/jsdelivr/files/polymer.platform",
    "localVersions": ["0.3.2", "0.3.3", "0.3.4", "0.3.5"],
    "remoteVersions": ["v0.0.20130816", "v0.0.20130829", "v0.0.20130905", "v0.0.20130912", "v0.0.20131003", "v0.0.20131010", "v0.0.20131025", "v0.0.20131107", "0.1.0", "0.1.1", "0.1.2", "0.1.3", "0.1.4", "0.2.0", "0.2.1", "0.2.2", "0.2.3", "0.2.4", "0.3.0", "0.3.1", "0.3.2", "0.3.3", "0.3.4", "0.3.5", "0.4.0"],
    "branchVersions": []
  },
  "version": "0.4.0",
  "updated": true,
  "updatePath": "/home/jsdelivr/files/polymer.platform/0.4.0",
  "branch": "platform/0.4.0"
}
```