Chart method to yahoo-finance

[reed-lawrence]

Basic functionality of the chart method within yahoo finance. Stylistically incomplete and needs polish, potential options parameters to modify the URL request.

Just wanted to contribute the basic functionality to perhaps expand upon.

[gadicc]

Thanks, @reed-lawrence, this is a welcome start!

One thing I did notice, is if you could please add:

var Promise = require('bluebird');

just to maintain consistency with the rest of the project (for the current major version, at least).

And maybe also some very rough docs :) Even if it just shows an example call with the example data returned?

@pilwon, not sure if you have any further thoughts?