Renamed groups to roles in the frontend

Working:
 Account
 Cost Centre
 Employee
 Product Group
 Product
 Role
 User
 Client

overlord/src/app/role/role.service.spec.ts

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