title: How to remove FloatingActionButton's surrounding shadow?
body: <p>I'm trying to replace the third party <a href="https://github.com/makovkastar/FloatingActionButton" rel="noreferrer">FloatingActionButton</a> with <a href="https://developer.android.com/reference/android/support/design/widget/FloatingActionButton.html" rel="noreferrer">the native one</a> which is packaged in library <code>com.android.support:design:22.2.0</code>.The default look has a dark shadow around the image,How can I get rid of it? I know the former one provides with the method <code>setShadow()</code>,but I just can't find similar one from the latter.</p>
  
  <p><img src="https://i.stack.imgur.com/iiKI3.png" alt="enter image description here"></p>
  
  <p>This is the related XML layout:</p>
  
  <pre><code>&lt;android.support.design.widget.FloatingActionButton
          android:id="@+id/alarm_front"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:src="@drawable/btn_icon_alarm_notset" /&gt;
  </code></pre>
  
  <p>And I have set its background color to yellow.</p>
  
  <pre><code>mAlarmBtn.setBackgroundTintList(ColorStateList.valueOf(getResources().getColor(R.color.floatButtonColor)));
  </code></pre>