title: Change Elevation of ActionBar by theme
body: <p>I want to remove the shadow below the ActionBar.</p>
  
  <p>I know that I need to change the elevation to 0dp, but I want to do it in the theme.</p>
  
  <p>For Android 4.4- I use : <code>&lt;item name="android:windowContentOverlay"&gt;@null&lt;/item&gt;</code></p>
  
  <p>But is it possible for Android 5.0 ?</p>