Fixes some bugs when a player chooses the '?' option

* We catch the NaN returned by parseInt() and decrease the number of valid votes
  to make the average more sensible.
* Added a ternary operator so that players with '?' values are sorted to the
  beginning of the results list.
* Use Math.round() and toFixed() to ensure we show human friendly numbers -
  instead of floats with 8 decimal places.