style and theming fixes (#428)

* fix generic error text and styles

* search input layout and style fixes

* settings theme

* layout theme support

* current user theme

* theming support for header component

* disable "use-host-property-decorator" tslint rule

* sorting picker button theme

src/app/components/preview/preview.component.ts

@@ -37,7 +37,6 @@ import { PageComponent } from '../page.component';
     templateUrl: 'preview.component.html',
     styleUrls: ['preview.component.scss'],
     encapsulation: ViewEncapsulation.None,
-    // tslint:disable-next-line:use-host-property-decorator
     host: { 'class': 'app-preview' }
 })
 export class PreviewComponent extends PageComponent implements OnInit {