refractor: shell (#287)

* Refractor components.
* Shift theme picker component to shared module.
* Shift progress bar service into its own folder.
* Add footer to app shell.
* Replace mat-icon by font-awesome icons.
* Fix sidenav visibility bug for handsets.
* Add comments.

Closes #286, Fixes #285

src/app/shared/theme-picker/theme-picker.component.spec.ts

@@ -0,0 +1,25 @@
+import { async, ComponentFixture, TestBed } from '@angular/core/testing';
+
+import { ThemePickerComponent } from './theme-picker.component';
+
+describe('ThemePickerComponent', () => {
+  let component: ThemePickerComponent;
+  let fixture: ComponentFixture<ThemePickerComponent>;
+
+  beforeEach(async(() => {
+    TestBed.configureTestingModule({
+      declarations: [ ThemePickerComponent ]
+    })
+    .compileComponents();
+  }));
+
+  beforeEach(() => {
+    fixture = TestBed.createComponent(ThemePickerComponent);
+    component = fixture.componentInstance;
+    fixture.detectChanges();
+  });
+
+  it('should create', () => {
+    expect(component).toBeTruthy();
+  });
+});