Add custom HTTP interceptor and spinner service for request handling; update CORS settings

jambotron-ui/src/app/services/spinner.service.spec.ts

@@ -0,0 +1,16 @@
+import { TestBed } from '@angular/core/testing';
+
+import { SpinnerService } from './spinner.service';
+
+describe('SpinnerService', () => {
+  let service: SpinnerService;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({});
+    service = TestBed.inject(SpinnerService);
+  });
+
+  it('should be created', () => {
+    expect(service).toBeTruthy();
+  });
+});

jambotron-ui/src/app/services/spinner.service.ts

@@ -0,0 +1,19 @@
+import { Injectable } from '@angular/core';
+import {BehaviorSubject} from 'rxjs';
+
+@Injectable({ providedIn: 'root'})
+export class SpinnerService {
+  visibility: BehaviorSubject<boolean>;
+
+  constructor() {
+    this.visibility = new BehaviorSubject(false);
+  }
+
+  show() {
+    this.visibility.next(true);
+  }
+
+  hide() {
+    this.visibility.next(false);
+  }
+}