Allow legend options to be updated

[Indigo744]

Legend options can now be updated in the update event.

$(".mapcontainer").trigger('update', [{
    legend : 
        area : {
            title :"Areas updated", 
            slices : [...]
        },
        plot :{
            title :"Cities updated",
            slices : [...]
        }}]);

Working JSFiddle: http://jsfiddle.net/60p8ukyn/1/

Related issue: #43

[Indigo744]

Sorry for this. I don't really understand what happened...

[neveldo]

Great new feature ! I have run some tests and it works fine. I just add a little comment on the source code.

[Indigo744]

As you suggested, I think once all PR are merged, I can make a new PR to remove the legends var.