Added ability to add data-attributes on the scatter charts. Send in a list of fields found in the data points, and only valid ones will become data attributes named after the data point.

e.g.

A data point has these values:
x = 1
y = 2
type = "typeA"

we call .dataAttributes(["type"] and the sag point will have the attribute data-type="typeA".

- kbuchanan (original author of changes)

Updating `Makefile` so it works (on OSX)