Table ending in empty cell

Currently, if the last cell of a table is empty, it will be dropped from the HTML:

```
| Header 1 | Header 2 |
|----------|----------|
| Cell 1   | Cell 2   |
| Cell 3   |          |
```

This pull request does the following:

1. Add test for situation described above
2. Fix bug causing the the last cell to not be added during conversion to HTML.