Add error dialog box.

- Add service for handling creation of error dialog.
- Refactor directory layout.

src/app/shared/error-dialog/error-dialog.component.spec.ts

@@ -0,0 +1,25 @@
+import { ComponentFixture, TestBed } from '@angular/core/testing';
+
+import { ErrorDialogComponent } from './error-dialog.component';
+
+describe('ErrorDialogComponent', () => {
+  let component: ErrorDialogComponent;
+  let fixture: ComponentFixture<ErrorDialogComponent>;
+
+  beforeEach(async () => {
+    await TestBed.configureTestingModule({
+      declarations: [ ErrorDialogComponent ]
+    })
+    .compileComponents();
+  });
+
+  beforeEach(() => {
+    fixture = TestBed.createComponent(ErrorDialogComponent);
+    component = fixture.componentInstance;
+    fixture.detectChanges();
+  });
+
+  it('should create', () => {
+    expect(component).toBeTruthy();
+  });
+});