Remove md-sidenav-layout alias for md-sidenav-container (#2283)

Author: mmalerba

src/lib/sidenav/sidenav.ts

@@ -303,7 +303,7 @@ export class MdSidenav implements AfterContentInit {
  */
 @Component({
   moduleId: module.id,
-  selector: 'md-sidenav-container, mat-sidenav-container, md-sidenav-layout, mat-sidenav-layout',
+  selector: 'md-sidenav-container, mat-sidenav-container',
   // Do not use ChangeDetectionStrategy.OnPush. It does not work for this component because
   // technically it is a sibling of MdSidenav (on the content tree) and isn't updated when MdSidenav
   // changes its state.