feat: add not found component (#327)

Fixes #110

src/app/not-found/not-found.component.spec.ts

@@ -0,0 +1,25 @@
+import { async, ComponentFixture, TestBed } from '@angular/core/testing';
+
+import { NotFoundComponent } from './not-found.component';
+
+describe('NotFoundComponent', () => {
+  let component: NotFoundComponent;
+  let fixture: ComponentFixture<NotFoundComponent>;
+
+  beforeEach(async(() => {
+    TestBed.configureTestingModule({
+      declarations: [ NotFoundComponent ]
+    })
+    .compileComponents();
+  }));
+
+  beforeEach(() => {
+    fixture = TestBed.createComponent(NotFoundComponent);
+    component = fixture.componentInstance;
+    fixture.detectChanges();
+  });
+
+  it('should create', () => {
+    expect(component).toBeTruthy();
+  });
+});