Convert the radialLinear scale to derive from Core.scale. Radial linear scale is now fit using the scale service. Added tests for the radialLinear scale.

src/core/core.controller.js

@@ -157,6 +157,8 @@
 				});
 
 				this.scale = scale;
+
+				this.scales['radialScale'] = scale;
 			}
 
 			Chart.scaleService.update(this, this.chart.width, this.chart.height);