Refine top 10 convictions table

[ghing]

Add the following columns:

• Explanation - a more human readable version of the charge
• Class - whether it's a felony or misdemeanor and the class of either

Alternately, instead of a separate explanation column, use a more immediately readable charge description.

[ghing]

@bepetersn also suggests showing the percent of total convictions instead of or in addition to the total count.

[ghing]

Many of the charges in the top 10 can be either a misdemeanor or a felony depending on whether it's a first offense or a subsequent offense (and the number of offenses varies by charge). I don't think we can clearly explain this in the limited space, so let's just leave out charge class.