Update confusion matrix to give both counts and normalized values in one figure

[nbagherzadeh]

We currently have the option to generate row-, and column-normalized confusion matrices, or non-normalized confusion matrices.

Having an option to generate normalized CM that also shows the counts are very helpful to better understand class-imbalances.

Example below:

[hannahilea]

Thoughts about making it a (/the) default implementation? I.e., update our current row- and column- normalized cm to include counts? Might be useful to have it visible by default rather than having yet another kwarg... In which case the action items would be:

• for row- and column-normalized cm, add count above (or below) the current normalized value
• for non-normalized cm, do nothing (?)

While we're at it, do we want to make the row- and column-normalized outputs percents? We don't currently do that...

[hannahilea]

Discussed with @nbagherzadeh; barring other opinions, we think this could/should be the default: all normalized plots also show a count above the fraction. For now, not converting to percent.