fix(tabs): remove inconsistent mdTabNav selector (#5170)

Author: jelbourn

src/lib/tabs/tab-nav-bar/tab-nav-bar.ts

@@ -36,7 +36,7 @@ import {Subject} from 'rxjs/Subject';
  */
 @Component({
   moduleId: module.id,
-  selector: '[md-tab-nav-bar], [mat-tab-nav-bar], [mdTabNav], [matTabNav]',
+  selector: '[md-tab-nav-bar], [mat-tab-nav-bar]',
   templateUrl: 'tab-nav-bar.html',
   styleUrls: ['tab-nav-bar.css'],
   host: {'class': 'mat-tab-nav-bar'},