Movie Reviews Example

If I incorporate less frequent words (say 5 or more, instead of 10 or more), `createJSON` tends to throw this warning --

```s
Warning message:
In .local(x, container, collapse, ..., .level = .level, .withNames = .withNames,  :
  non-fininte values in numeric vector may not be approriately represented in JSON
```

This seems to be an issue with the numerical precision of converting log-probabilities from R to JSON...