feat(components): add a tree view page

src/app/pages/components/tree/tree.component.html

@@ -0,0 +1,10 @@
+<div class="row">
+  <div class="col-md-6">
+    <nga-card>
+      <nga-card-header>Tree</nga-card-header>
+      <nga-card-body>
+        <tree [tree]="tree"></tree>
+      </nga-card-body>
+    </nga-card>
+  </div>
+</div>

src/app/pages/components/tree/tree.component.ts

@@ -0,0 +1,33 @@
+import { Component } from '@angular/core';
+import { TreeModel } from 'ng2-tree';
+
+@Component({
+  selector: 'ngx-tree',
+  templateUrl: './tree.component.html',
+})
+export class TreeComponent {
+
+  tree: TreeModel = {
+    value: 'Programming languages by programming paradigm',
+    children: [{
+      value: 'Object-oriented programming',
+      children: [{
+        value: 'Java',
+      }, {
+        value: 'C++',
+      }, {
+        value: 'C#',
+      }],
+    }, {
+      value: 'Prototype-based programming',
+      children: [{
+        value: 'JavaScript',
+      }, {
+        value: 'CoffeeScript',
+      }, {
+        value: 'Lua',
+      }],
+    }],
+  };
+
+}