Made some progress in fetching percentiles.

Still need to figure out how to sort the times and pick the offset.
Get approximate indexes for a given percentile.

It gets pretty close, in any case it is presently more accurate than an
average would be.
Update template and runs page for new data.
Add very basic test and fix offset error with getPercentileForUrl.
Merge branch 'percentile-fetch'

Graphs generated on the URL summary now use percentile values instead of
averages. This gives a more useful representation of performance when
large/small outliers are involved.

Closes #37, #28