title: Add selectableItemBackground to CardView
body: <p>I want to set the foreground of my <a href="http://developer.android.com/reference/android/support/v7/widget/CardView.html" rel="noreferrer">CardView</a> to <code>?attr/selectableItemBackground</code>.</p>
  
  <p>It work's when I declare the foreground in xml:</p>
  
  <pre><code>android:foreground="?attr/selectableItemBackground"
  </code></pre>
  
  <p>But I want to set the foreground programmatically. This doesn't work:</p>
  
  <pre><code>int[] attrs = new int[]{R.attr.color_a, R.attr.selectableItemBackground};
  TypedArray ta = context.obtainStyledAttributes(attrs);
  mColorA = ta.getColor(0, 0);
  mSelectableItemBackground = ContextCompat.getDrawable(context, ta.getResourceId(1, 0));
  ta.recycle();
  
  ...
  
  cardView.setOnClickListener(onClickListener);
  cardView.setClickable(true);
  cardView.setForeground(mSelectableItemBackground);
  </code></pre>
  
  <p>However, retrieving the attributes works (mSelectableItemBackground contains a <code>RippleDrawable</code>), but the foreground doesn't change when I press on the Card.</p>