title: Android design library TabLayout background issues
body: <p>When I setup the tabBackground attribute of the "22.2.0 Android design library"  TabLayout (android.support.design.widget.TabLayout) two problems appear :</p>
  
  <ul>
  <li>The ripple effect in the tabs is lost</li>
  <li>The tab indicator disappears. </li>
  </ul>
  
  <p>This occurs on both Lollipop and Kitkat devices.</p>
  
  <p>Without the tabBackground settings, both ripple effect and tab indicator work but the background has a default color that is different from the toobar, which is not exactly conform to the material design guidelines.</p>
  
  <p>Please find below the XML :</p>
  
  <pre><code> &lt;android.support.design.widget.TabLayout
          android:id="@+id/tabLayout"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          app:tabMode="fixed"
          app:tabGravity="fill"
          app:tabBackground = "?attr/colorPrimary" /&gt;
  </code></pre>