title: Can't use android:background with button from the new material components
body: <p>I'm using the new material components <code>com.google.android.material:material</code> with android x but I can't set a custom background to the button.</p>
  
  <p>I know that I can use <code>app:backgroundTint</code> to change the color</p>
  
  <p>but the default background has some padding that I want to get rid of, and the old way of using <code>android:background</code> to set my own background but this is no longer working.</p>
  
  <p>I looked at the <a href="https://github.com/material-components/material-components-android/blob/master/docs/components/MaterialButton.md" rel="noreferrer">docs</a> but can't find any mention to this change.</p>