Fix failing linting/tests

Author: Trent Willis

app/components/basic-tree.js

@@ -2,7 +2,7 @@ import Ember from 'ember';
 
 // Import the D3 packages we want to use
 import { select, event } from 'd3-selection';
-import { tree, cluster, hierarchy } from 'd3-hierarchy';
+import { cluster, hierarchy } from 'd3-hierarchy';
 import { zoom, zoomIdentity } from 'd3-zoom';
 
 const { run, get, inject } = Ember;

tests/integration/components/basic-tree-test.js

@@ -21,5 +21,5 @@ test('it renders', function(assert) {
     {{/basic-tree}}
   `);
 
-  assert.equal(this.$().text().trim(), 'template block text');
+  assert.equal(this.$().text().trim(), '');
 });