Buttons on Bulletin do not work

**Problem Description:**
The action buttons/handlers do not work.

**Steps to reproduce:**
1. Install via Pods
2. `@import BLTNBoard`
3.
```
BLTNPageItem *page = [[BLTNPageItem alloc] initWithTitle:@"Notifications"];
page.descriptionText = @"Receieve latest news.";
page.actionButtonTitle = @"Allow";
page.alternativeButtonTitle = @"Decide later";

page.actionHandler = ^(BLTNActionItem * _Nonnull _item) {
[self requestNotifications];
};

BLTNPageItem *introPage = page;
BLTNItemManager *man = [[BLTNItemManager alloc] initWithRootItem:introPage];

[man showBulletinAboveViewController:self animated:YES completion:nil];
```
4. Launch the app
5. Tap `Allow` on the `BulletinBoard`
6. Nothing happens. Tapping the ( X ) in the top right doesn't commit any action either.

**Environment:**
- Device: iPhone X
- OS: iOS 12.1.x / Xcode 10.1
- Version of BulletinBoard: 3.0.0