Bills initially working just as proof of concept

ng linted
modifier categories list is better at displaying data sanely now

bookie/src/app/sales/bill.service.spec.ts

@@ -0,0 +1,12 @@
+import { TestBed } from '@angular/core/testing';
+
+import { BillService } from './bill.service';
+
+describe('BillService', () => {
+  beforeEach(() => TestBed.configureTestingModule({}));
+
+  it('should be created', () => {
+    const service: BillService = TestBed.get(BillService);
+    expect(service).toBeTruthy();
+  });
+});