Workaround for bug 984928

Two things:
 * Don't use minified CDN hosted sources for nvd3 and d3
 * Discard negative means and percentiles.

I'm not sure why we ever get negative means or percentiles. Should we **ever** get that?

Is it because of integer overflow?

Note, this doesn't really fix much... It's just makes the problem go away until somebody notices missing entries :)