Added delete confirmation dialogs for both Shows and Episodes

We want to make sure you don't accidentally delete your podcast or your episodes, so we've added some confirmation steps to the process.

How to delete a podcast episode

1. Go to the "Episodes" tab.

2. Click "Edit" on the episode you'd like to delete.

3. Scroll to the bottom, and click on the "Delete" button in the lower-right corner.

4. Confirm that you really want to delete the episode!