make a better grunt dot

this.files的结构是这样的：
```
[{
    "src": ["src/templates/basic.html"],
    "dest": "lib/templates/basic.html",
    "orig": {
        "expand": true,
        "cwd": "src/",
        "src": ["**/*.html"],
        "dest": "lib/"
    }
}]
[{
    "src": ["src/templates/task.html", "src/templates/event.html"],
    "dest": "lib/templates/task.js",
    "orig": {
        "src": ["src/templates/task.html", "src/templates/event.html"],
        "dest": "lib/templates/task.js"
    }
}]
```

我目前的做法是把src合到一起，define成一个模块