Ensure swapping graphData clears and restarts.

Author: Robert Jackson

app/components/basic-tree.js

@@ -53,7 +53,10 @@ export default Ember.Component.extend({
   },
 
   drawTree(data) {
-    let svg = select(this.element.querySelector('.svg-container'))
+    let svgContainer = this.element.querySelector('.svg-container');
+    svgContainer.innerHTML = '';
+
+    let svg = select(svgContainer)
         .append("svg")
         .attr("preserveAspectRatio", "xMinYMin meet")
         .attr("viewBox", "0 0 300 300")