Spanish short forms: final graph for Spanish L2 short form doesn't seem right and need scoring

[vmarchman]

@HenryMehta The final graph on the splash page for Spanish L2 short form doesn't seem right. Seems to give an equal number of items per page and doesn't pull out "hardest" item.

Also, we don't seem to be computing percentiles for the Spanish short forms. I will give you tables for these.