Can h5tojson suppress fill value?

I'm wondering it has a similar option that h5perf [1] provides:

```
-n, --no-fill   Specifies to not write fill values to HDF5 datasets. This option is supported only in HDF5 Release v1.6 or later. 
(Default: Off, i.e., write fill values)
```

[1] https://www.hdfgroup.org/HDF5/doc1.6/Tools.html#Tools-Dump
