message: fix(popover): fix undefined container class
diff: @@ -37,7 +37,7 @@ export class PopoverDirective implements OnInit, OnDestroy {
  /**
  * Css class for popover container
  */
  - @Input() public containerClass: string;
  + @Input() public containerClass: string = '';
  /**
  * Returns whether or not the popover is currently being shown
  