title: Add elevation/shadow on toolbar for pre-lollipop devices
body: <p>I updated my android app to the new material design, but I also wanted to add some shadow or elevation to the Toolbar. There seem to be some (hacky) ways of doing it via images/9-patches, but I wonder if it can be done via the support libraries. (just like the <code>CardView</code> can have elevation)</p>
  
  <p>According to <a href="https://stackoverflow.com/a/31026359/1756547">this</a> answer on another question, this is possible by wrapping the <code>Toolbar</code> in a <code>AppBarLayout</code>, but this doesn't work for me.</p>
  
  <p><strong>My layout:</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.design.widget.AppBarLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"&gt;
      &lt;android.support.v7.widget.Toolbar
              android:id="@+id/Toolbar"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:minHeight="?attr/actionBarSize"
              android:background="?attr/colorPrimary"
              android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
              app:popupTheme="@style/ThemeOverlay.AppCompat.Light" /&gt;
  &lt;/android.support.design.widget.AppBarLayout&gt;
  </code></pre>
  
  <p>I also tried setting elevation via XML and through code, but that doesn't work either.</p>
  
  <p>Any help would be appreciated! Thanks in advance.</p>
  
  <p><strong>Update:</strong></p>
  
  <p>Since I include my Toolbar layout in my other layouts, below is one of my main layouts:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
      android:layout_width="match_parent"
      android:layout_height="match_parent"&gt;
      &lt;include
          layout="@layout/Toolbar" /&gt;
      &lt;fragment
          class="OverAllField.XamarinAndroid.Fragments.Planning.PlanningFragment"
          android:id="@+id/PlanningFragment"
          android:layout_width="match_parent"
          android:layout_height="0dp"
          android:layout_weight="1" /&gt;
  &lt;/LinearLayout&gt;
  </code></pre>