title: AppBarLayout and Toolbar set no shadow
body: <p>I have <code>AppBarLayout</code> and <code>Toolbar</code> in acitivty and <code>TabLayout</code> into my Fragment. How can I set my toolbar shadow to zero so it would be smooth place between toolbar and tablayout?</p>
  
  <pre><code>&lt;android.support.design.widget.AppBarLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:elevation="0dp"
      android:theme="@style/SDK.Theme.AppBarOverlay"&gt;
  
      &lt;android.support.v7.widget.Toolbar
          android:id="@+id/toolbar"
          android:layout_width="match_parent"
          android:layout_height="?attr/actionBarSize"
          android:minHeight="?attr/actionBarSize"
          app:elevation="0dp"
          local:popupTheme="@style/ThemeOverlay.AppCompat.Light"
          local:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"&gt;
  </code></pre>