title: Ask for permissions with facebook login button
body: <p>I have the facebook login widget, defined in my xml as:</p>
  
  <pre><code>&lt;com.facebook.widget.LoginButton
          xmlns:fb="http://schemas.android.com/apk/res-auto"
          android:id="@+id/login_button"
          android:layout_width="310dp"
          android:layout_height="50dp"
          android:text="@string/login_facebook"
          android:gravity="center_horizontal"
          android:textSize="15sp"
          android:textColor="@color/black"
          android:scaleType="centerInside"
          fb:login_text="@string/login_facebook"
          fb:logout_text="@string/login_facebook"
          android:contentDescription="@string/login_facebook"
          android:background="@drawable/login_activity_facebook_unpressed"
          /&gt;
  </code></pre>
  
  <p>With no extra code whatsoever used then clicking on this button will take the user to the permissions page for facebook and ask for "public profile" information. I want to also ask for the email permission. How can I override the default click behaviour of the facebook widget so that it asks for email permissions when it is clicked on?</p>
  
  <p>I've tried inserting extra code, but it always invokes the default "public profile" logic before reaching anything else. </p>