Indent for body and head when using html:*

I often use `html:5` to start a html file. But I never liked that the `<head>` and `<body>` do not have indent. Each time I was selecting them and adding the indent. 

Finally I decided to edit the plugin and I added this functionality. So, when `html:5_` will be expanded it will be transformed in:

```html
<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
        _
    </body>
</html>
```

(`_` being the cursor position)

Thank you for this great plugin! :smiley: