Card Groups and Decks don't play nicely with footers

Created by: lunged

Applying a footer to cards arranged as groups or decks doesn't work as expected.

The footer only appears at the bottom of the card(s) with the tallest content. The footer simply appears below the content in all other cards, not at the bottom.

<div class="card-deck-wrapper">
 <div class="card-deck">

 <div class="card">
  <img class="card-img-top" src="img/image.jpg" alt="Card image cap">
  <div class="card-block">
   <h4 class="card-title">Card title</h4>
   <p class="card-text">Content in Here.</p>
  </div>
  <div class="card-footer"><a class="btn btn-block btn-success-outline">BUTTON</a></div>
 </div>
...

</div>
</div>