Scaffolding causes exception when passing an empty string for file content

When using a file in the output that contains an empty string such as:

```javascript
{
  output: {
    'index.html': ''
  }
}
```

You get an exception of: 

```Unhandled exception: Error: You must pass a string or Handlebars AST to Handlebars.compile. You passed```

For some reason Handlebars blows up when you pass an empty string to `Handlebars.compile`. Providing a workaround until this is resolved.