title: Cardview, cardCornerRadius not working
body: <p>I'm trying to set to my cards a <code>cardCornerRadius</code> but its not working. </p>
  
  <p>Take a look my code below:</p>
  
  <p><strong>CardView</strong> where the last property is the <code>cardCornerRadius</code></p>
  
  <pre><code>&lt;android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      android:id="@+id/user_card_view"
      android:layout_width="match_parent"
      android:layout_height="@dimen/card_height"
      android:layout_gravity="center"
      android:layout_marginBottom="@dimen/md_keylines"
      android:layout_marginLeft="@dimen/md_keylines"
      android:layout_marginRight="@dimen/md_keylines"
      android:foreground="?attr/selectableItemBackground"
      android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
      app:cardCornerRadius="3dp"&gt;
  </code></pre>
  
  <p><strong>Dependencies</strong></p>
  
  <blockquote>
    <p>compile 'com.android.support:appcompat-v7:23.3.0'
    compile 'com.android.support:design:23.3.0'
    compile 'com.android.support:cardview-v7:23.3.0'</p>
  </blockquote>
  
  <p>I didn't get any error in the console, so I really don't know what is happening. </p>
  
  <p>Any idea how to do it?</p>
  
  <p>Thanks!</p>