add setOptions function, revised update function to allow for new options

[mezmi]

Added a setOptions function and revised the update function to allow for new options to be passed to the chart.
Example.

 $('#modalChart').data('easyPieChart').update(chartPercent, {
                    scaleColor: false,
                    barColor: chartBarColor,
                    trackColor: '#ccc'
                });

[mezmi]

@rendro Any ideas why this Travis CI build fails? Details are a bit sketchy...

PhantomJS is complaining saying this:
angular easypiechart directive should have percentage default value 0

I didn't mess with any of the default values, simply added another parameter to the update function and included 7ever's setOptions function.

Everything seems to function properly on my end.

[rendro]

@enkimatt Don't worry about the Travis CI results. The rest cases are broken at the moment. I'll have a look at your PR soon. Thanks for your contribution.

[mezmi]

My contribution is minimal, I should be thanking you - so, Thank you.. LOL. This chart is awesome.