added underscore dependency and enabled array manipulations

[jithinbp]

• Added ember-cli-underscore
• controllers/user-home.js checks the 'stacking' argument of data passed to the plot, and makes a transpose of [xdata,ydata] if necessary
• fixed some pending eslint warnings

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small change I'm unable to make : Can't call the replot method on an existing plot

// alert(JSON.stringify($(`#${actionDefinition.success.target}`).data(), null, 4));
// $(`#${actionDefinition.success.target}`).data('jqplot').replot({ data: [_.zip.apply(null, resultValue)] });
$.jqplot(actionDefinition.success.target, [_.zip.apply(null, resultValue)]).replot();

Uncomment the alert to see that data attached to the jquery selector is {} even though the plot was created in that div by a component. The selector works fine with a regular small js snippet, and according to the docs, it is the correct way to update a plot. @niranjan94 any suggestions on why there seem to be no methods attached to the selector (I've cross checked with chrome's inspector) ? Another way is to store a global variable referencing the plot, but I would prefer the selector.

fixed #68