Formatter: JSON output should return all counts

[ryelle]

In most audits, it shows "Top 10 most used …". This was done to avoid overwhelming the CLI screen from too much information, given how large the results can be on core CSS (even just single reports, like colors).

For the new JSON output (--format=json), this does not need to be human readable, so we can return the full result set for all values.

This might need to change the way audits return report objects.