Remove the 'moderate' filtering option from officeimporter application

Currently officeimporter application offers three different style filtering options:

1. Strict - Filter all styles.

2. None - Filter nothing.

3. Moderate - Only keep those styles without which the output would be drastically different from the original document (ex: alignments, image widths etc.)

As you can see the third option is hard to define and can be confusing to the user whereas the first to options are very clear and makes a lot of sense.

We should remove the third option and provide only one option (checkbox) which allows either to keep all styles or remove all of them.