Add accessor functions for canvas and ctx within the CanvasRenderer class. This allows you to use a gradient fill inside the barColor function.
Merge branch 'gradient' of github.com:quikly/easy-pie-chart into quikly-gradient

Conflicts:
	dist/angular.easypiechart.min.js
	dist/easypiechart.min.js
	dist/jquery.easypiechart.min.js
added plugin api information