Defined Properties with "" value are not replaced

With a template that looks like this:

```
Test {{ me_value }}
```

And a variables file that looks like this:

```
{
  "me_value": ""
}
```

The script outputs the following:

```
Test me_value
```

However, it should be:
```
Test  
```

Since the value is defined, it's just empty.

Oh and.. Thank you for creating this amazing tool!