feat(accounting): add frequent postings component

Add frequent postings component to create a journal entry.

Fixes #136

src/app/accounting/accounting.service.spec.ts

@@ -0,0 +1,15 @@
+import { TestBed, inject } from '@angular/core/testing';
+
+import { AccountingService } from './accounting.service';
+
+describe('AccountingService', () => {
+  beforeEach(() => {
+    TestBed.configureTestingModule({
+      providers: [AccountingService]
+    });
+  });
+
+  it('should be created', inject([AccountingService], (service: AccountingService) => {
+    expect(service).toBeTruthy();
+  }));
+});