Add pipe and implement to dashboard/device component

webapp/frontend/src/app/shared/device-hours.pipe.spec.ts

@@ -0,0 +1,9 @@
+import { DeviceHoursPipe } from './device-hours.pipe';
+
+
+describe('DeviceHoursPipe', () => {
+  it('create an instance', () => {
+    const pipe = new DeviceHoursPipe();
+    expect(pipe).toBeTruthy();
+  });
+});